61646639 has 4 divisors (see below), whose sum is σ = 62090280. Its totient is φ = 61203000.

The previous prime is 61646603. The next prime is 61646653. The reversal of 61646639 is 93664616.

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

It is a cyclic number.

It is not a de Polignac number, because 61646639 - 2²⁰ = 60598063 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 61646596 and 61646605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61646239) 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, 221612 + ... + 221889.

It is an arithmetic number, because the mean of its divisors is an integer number (15522570).

Almost surely, 2^61646639 is an apocalyptic number.

61646639 is a deficient number, since it is larger than the sum of its proper divisors (443641).

61646639 is a wasteful number, since it uses less digits than its factorization.

61646639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 443640.

The product of its digits is 139968, while the sum is 41.

The square root of 61646639 is about 7851.5373653827. The cubic root of 61646639 is about 395.0358115264.

The spelling of 61646639 in words is "sixty-one million, six hundred forty-six thousand, six hundred thirty-nine".