139972561 has 3 divisors (see below), whose sum is σ = 139984393. Its totient is φ = 139960730.

The previous prime is 139972541. The next prime is 139972579. The reversal of 139972561 is 165279931.

The square root of 139972561 is 11831.

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 is not a de Polignac number, because 139972561 - 2¹¹ = 139970513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (139972541) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 5916 + ... + 17746.

Almost surely, 2^139972561 is an apocalyptic number.

139972561 is the 11831-st square number.

139972561 is the 5916-th centered octagonal number.

It is an amenable number.

139972561 is a deficient number, since it is larger than the sum of its proper divisors (11832).

139972561 is an frugal number, since it uses more digits than its factorization.

139972561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23662 (or 11831 counting only the distinct ones).

The product of its digits is 102060, while the sum is 43.

The cubic root of 139972561 is about 519.2154849102.

The spelling of 139972561 in words is "one hundred thirty-nine million, nine hundred seventy-two thousand, five hundred sixty-one".