28576721 has 2 divisors, whose sum is σ = 28576722. Its totient is φ = 28576720.

The previous prime is 28576663. The next prime is 28576727. The reversal of 28576721 is 12767582.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18105025 + 10471696 = 4255^2 + 3236^2 .

It is a cyclic number.

It is not a de Polignac number, because 28576721 - 2¹⁸ = 28314577 is a prime.

It is a super-2 number, since 2×28576721² = 1633257966223682, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28576727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14288360 + 14288361.

It is an arithmetic number, because the mean of its divisors is an integer number (14288361).

Almost surely, 2^28576721 is an apocalyptic number.

It is an amenable number.

28576721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28576721 is an equidigital number, since it uses as much as digits as its factorization.

28576721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47040, while the sum is 38.

The square root of 28576721 is about 5345.7198766864. The cubic root of 28576721 is about 305.7295836752.

The spelling of 28576721 in words is "twenty-eight million, five hundred seventy-six thousand, seven hundred twenty-one".