61657639 has 4 divisors (see below), whose sum is σ = 62128440. Its totient is φ = 61186840.

The previous prime is 61657637. The next prime is 61657663. The reversal of 61657639 is 93675616.

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 61657639 - 2¹ = 61657637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 61657595 and 61657604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61657633) 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, 235204 + ... + 235465.

It is an arithmetic number, because the mean of its divisors is an integer number (15532110).

Almost surely, 2^61657639 is an apocalyptic number.

61657639 is a deficient number, since it is larger than the sum of its proper divisors (470801).

61657639 is a wasteful number, since it uses less digits than its factorization.

61657639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470800.

The product of its digits is 204120, while the sum is 43.

The square root of 61657639 is about 7852.2378338917. The cubic root of 61657639 is about 395.0593063758.

The spelling of 61657639 in words is "sixty-one million, six hundred fifty-seven thousand, six hundred thirty-nine".