61656639 has 24 divisors (see below), whose sum is σ = 93493680. Its totient is φ = 36072960.

The previous prime is 61656631. The next prime is 61656641. The reversal of 61656639 is 93665616.

It is not a de Polignac number, because 61656639 - 2³ = 61656631 is a prime.

It is a super-5 number, since 5×61656639⁵ (a number of 40 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 61656639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61656631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7599 + ... + 13455.

It is an arithmetic number, because the mean of its divisors is an integer number (3895570).

Almost surely, 2^61656639 is an apocalyptic number.

61656639 is a deficient number, since it is larger than the sum of its proper divisors (31837041).

61656639 is a wasteful number, since it uses less digits than its factorization.

61656639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5911 (or 5900 counting only the distinct ones).

The product of its digits is 174960, while the sum is 42.

The square root of 61656639 is about 7852.1741575184. The cubic root of 61656639 is about 395.0571705959.

It can be divided in two parts, 616566 and 39, that added together give a triangular number (616605 = T₁₁₁₀).

The spelling of 61656639 in words is "sixty-one million, six hundred fifty-six thousand, six hundred thirty-nine".