28640690 has 64 divisors (see below), whose sum is σ = 58786560. Its totient is φ = 9972480.

The previous prime is 28640687. The next prime is 28640693. The reversal of 28640690 is 9604682.

It is an interprime number because it is at equal distance from previous prime (28640687) and next prime (28640693).

It is a super-2 number, since 2×28640690² = 1640578247352200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 28640690.

It is not an unprimeable number, because it can be changed into a prime (28640693) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 267617 + ... + 267723.

It is an arithmetic number, because the mean of its divisors is an integer number (918540).

Almost surely, 2^28640690 is an apocalyptic number.

28640690 is an abundant number, since it is smaller than the sum of its proper divisors (30145870).

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

28640690 is a wasteful number, since it uses less digits than its factorization.

28640690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 28640690 is about 5351.6997299923. The cubic root of 28640690 is about 305.9575389272.

The spelling of 28640690 in words is "twenty-eight million, six hundred forty thousand, six hundred ninety".