28939640 has 16 divisors (see below), whose sum is σ = 65114280. Its totient is φ = 11575840.

The previous prime is 28939637. The next prime is 28939697. The reversal of 28939640 is 4693982.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 361706 + ... + 361785.

Almost surely, 2^28939640 is an apocalyptic number.

28939640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28939640 is an abundant number, since it is smaller than the sum of its proper divisors (36174640).

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

28939640 is a wasteful number, since it uses less digits than its factorization.

28939640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723502 (or 723498 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 41.

The square root of 28939640 is about 5379.5576026287. The cubic root of 28939640 is about 307.0183792892.

The spelling of 28939640 in words is "twenty-eight million, nine hundred thirty-nine thousand, six hundred forty".