28029981 has 16 divisors (see below), whose sum is σ = 42799104. Its totient is φ = 15984624.

The previous prime is 28029977. The next prime is 28030007. The reversal of 28029981 is 18992082.

It is not a de Polignac number, because 28029981 - 2² = 28029977 is a prime.

It is a super-2 number, since 2×28029981² = 1571359669720722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28029901) 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, 12556 + ... + 14618.

It is an arithmetic number, because the mean of its divisors is an integer number (2674944).

Almost surely, 2^28029981 is an apocalyptic number.

28029981 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28029981 is a deficient number, since it is larger than the sum of its proper divisors (14769123).

28029981 is a wasteful number, since it uses less digits than its factorization.

28029981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2720.

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 28029981 is about 5294.3348024091. The cubic root of 28029981 is about 303.7672394490.

The spelling of 28029981 in words is "twenty-eight million, twenty-nine thousand, nine hundred eighty-one".