28781520 has 40 divisors (see below), whose sum is σ = 89223456. Its totient is φ = 7675008.

The previous prime is 28781509. The next prime is 28781537. The reversal of 28781520 is 2518782.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

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, 59722 + ... + 60201.

Almost surely, 2^28781520 is an apocalyptic number.

28781520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28781520 is an abundant number, since it is smaller than the sum of its proper divisors (60441936).

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

28781520 is a wasteful number, since it uses less digits than its factorization.

28781520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119939 (or 119933 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 33.

The square root of 28781520 is about 5364.8410973672. The cubic root of 28781520 is about 306.4581969002.

The spelling of 28781520 in words is "twenty-eight million, seven hundred eighty-one thousand, five hundred twenty".