28812021 has 16 divisors (see below), whose sum is σ = 44926464. Its totient is φ = 16080624.

The previous prime is 28811983. The next prime is 28812023. The reversal of 28812021 is 12021882.

It is not a de Polignac number, because 28812021 - 2⁹ = 28811509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 28811982 and 28812000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28812023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15051 + ... + 16856.

It is an arithmetic number, because the mean of its divisors is an integer number (2807904).

Almost surely, 2^28812021 is an apocalyptic number.

28812021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28812021 is a deficient number, since it is larger than the sum of its proper divisors (16114443).

28812021 is a wasteful number, since it uses less digits than its factorization.

28812021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31960.

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 28812021 is about 5367.6830197023. The cubic root of 28812021 is about 306.5664142738.

The spelling of 28812021 in words is "twenty-eight million, eight hundred twelve thousand, twenty-one".