28572021 has 10 divisors (see below), whose sum is σ = 42681782. Its totient is φ = 19047960.

The previous prime is 28572001. The next prime is 28572073. The reversal of 28572021 is 12027582.

It can be written as a sum of positive squares in only one way, i.e., 22667121 + 5904900 = 4761^2 + 2430^2 .

It is not a de Polignac number, because 28572021 - 2¹¹ = 28569973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28572001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 176290 + ... + 176451.

Almost surely, 2^28572021 is an apocalyptic number.

It is an amenable number.

28572021 is a deficient number, since it is larger than the sum of its proper divisors (14109761).

28572021 is an equidigital number, since it uses as much as digits as its factorization.

28572021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 352753 (or 352744 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 28572021 is about 5345.2802545797. The cubic root of 28572021 is about 305.7128216888.

The spelling of 28572021 in words is "twenty-eight million, five hundred seventy-two thousand, twenty-one".