64657391 has 4 divisors (see below), whose sum is σ = 64680000. Its totient is φ = 64634784.

The previous prime is 64657381. The next prime is 64657421. The reversal of 64657391 is 19375646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19375646 = 2 ⋅9687823.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64657391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64657321) 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, 6266 + ... + 12983.

It is an arithmetic number, because the mean of its divisors is an integer number (16170000).

Almost surely, 2^64657391 is an apocalyptic number.

64657391 is a deficient number, since it is larger than the sum of its proper divisors (22609).

64657391 is a wasteful number, since it uses less digits than its factorization.

64657391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22608.

The product of its digits is 136080, while the sum is 41.

The square root of 64657391 is about 8040.9819673968. The cubic root of 64657391 is about 401.3649018930.

The spelling of 64657391 in words is "sixty-four million, six hundred fifty-seven thousand, three hundred ninety-one".