139628521561 has 3 divisors (see below), whose sum is σ = 139628895231. Its totient is φ = 139628147892.

The previous prime is 139628521559. The next prime is 139628521573. The reversal of 139628521561 is 165125826931.

The square root of 139628521561 is 373669.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 21471333961 + 118157187600 = 146531^2 + 343740^2 .

It is not a de Polignac number, because 139628521561 - 2¹ = 139628521559 is a prime.

It is a super-2 number, since 2×139628521561² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (139628521961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 186835 + ... + 560503.

It is an arithmetic number, because the mean of its divisors is an integer number (46542965077).

Almost surely, 2^139628521561 is an apocalyptic number.

139628521561 is the 373669-th square number.

139628521561 is the 186835-th centered octagonal number.

It is an amenable number.

139628521561 is a deficient number, since it is larger than the sum of its proper divisors (373670).

139628521561 is an frugal number, since it uses more digits than its factorization.

139628521561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 747338 (or 373669 counting only the distinct ones).

The product of its digits is 777600, while the sum is 49.

Multiplying 139628521561 by its sum of digits (49), we get a square (6841797556489 = 2615683²).

The spelling of 139628521561 in words is "one hundred thirty-nine billion, six hundred twenty-eight million, five hundred twenty-one thousand, five hundred sixty-one".