64657640 has 32 divisors (see below), whose sum is σ = 145774080. Its totient is φ = 25810752.

The previous prime is 64657631. The next prime is 64657651. The reversal of 64657640 is 4675646.

It is a super-2 number, since 2×64657640² = 8361220820739200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 64657594 and 64657603.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22949 + ... + 25611.

It is an arithmetic number, because the mean of its divisors is an integer number (4555440).

Almost surely, 2^64657640 is an apocalyptic number.

It is an amenable number.

64657640 is an abundant number, since it is smaller than the sum of its proper divisors (81116440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

64657640 is a wasteful number, since it uses less digits than its factorization.

64657640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3281 (or 3277 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 38.

The square root of 64657640 is about 8040.9974505654. The cubic root of 64657640 is about 401.3654171201.

The spelling of 64657640 in words is "sixty-four million, six hundred fifty-seven thousand, six hundred forty".