61640462581 has 4 divisors (see below), whose sum is σ = 61641666252. Its totient is φ = 61639258912.

The previous prime is 61640462573. The next prime is 61640462603. The reversal of 61640462581 is 18526404616.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 48403960081 + 13236502500 = 220009^2 + 115050^2 .

It is a cyclic number.

It is not a de Polignac number, because 61640462581 - 2³ = 61640462573 is a prime.

It is a super-2 number, since 2×61640462581² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61640462551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 521440 + ... + 628633.

It is an arithmetic number, because the mean of its divisors is an integer number (15410416563).

Almost surely, 2^61640462581 is an apocalyptic number.

It is an amenable number.

61640462581 is a deficient number, since it is larger than the sum of its proper divisors (1203671).

61640462581 is a wasteful number, since it uses less digits than its factorization.

61640462581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1203670.

The product of its (nonzero) digits is 276480, while the sum is 43.

The spelling of 61640462581 in words is "sixty-one billion, six hundred forty million, four hundred sixty-two thousand, five hundred eighty-one".