61615581 has 4 divisors (see below), whose sum is σ = 82154112. Its totient is φ = 41077052.

The previous prime is 61615573. The next prime is 61615663. The reversal of 61615581 is 18551616.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 61615581 - 2³ = 61615573 is a prime.

It is a super-2 number, since 2×61615581² = 7592959643935122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61615511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10269261 + ... + 10269266.

It is an arithmetic number, because the mean of its divisors is an integer number (20538528).

Almost surely, 2^61615581 is an apocalyptic number.

It is an amenable number.

61615581 is a deficient number, since it is larger than the sum of its proper divisors (20538531).

61615581 is a wasteful number, since it uses less digits than its factorization.

61615581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20538530.

The product of its digits is 7200, while the sum is 33.

The square root of 61615581 is about 7849.5592869918. The cubic root of 61615581 is about 394.9694597976.

The spelling of 61615581 in words is "sixty-one million, six hundred fifteen thousand, five hundred eighty-one".