28376721 has 24 divisors (see below), whose sum is σ = 42007680. Its totient is φ = 18454176.

The previous prime is 28376717. The next prime is 28376729. The reversal of 28376721 is 12767382.

It is not a de Polignac number, because 28376721 - 2² = 28376717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28376729) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 75891 + ... + 76263.

It is an arithmetic number, because the mean of its divisors is an integer number (1750320).

Almost surely, 2^28376721 is an apocalyptic number.

It is an amenable number.

28376721 is a deficient number, since it is larger than the sum of its proper divisors (13630959).

28376721 is a wasteful number, since it uses less digits than its factorization.

28376721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 565 (or 562 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 28376721 is about 5326.9804767804. The cubic root of 28376721 is about 305.0146763519.

The spelling of 28376721 in words is "twenty-eight million, three hundred seventy-six thousand, seven hundred twenty-one".