28809981 has 6 divisors (see below), whose sum is σ = 41614430. Its totient is φ = 19206648.

The previous prime is 28809967. The next prime is 28809983. The reversal of 28809981 is 18990882.

It can be written as a sum of positive squares in only one way, i.e., 28676025 + 133956 = 5355^2 + 366^2 .

It is not a de Polignac number, because 28809981 - 2¹⁰ = 28808957 is a prime.

It is a super-2 number, since 2×28809981² = 1660030010440722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28809983) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1600546 + ... + 1600563.

Almost surely, 2^28809981 is an apocalyptic number.

It is an amenable number.

28809981 is a deficient number, since it is larger than the sum of its proper divisors (12804449).

28809981 is a wasteful number, since it uses less digits than its factorization.

28809981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3201115 (or 3201112 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The square root of 28809981 is about 5367.4929902143. The cubic root of 28809981 is about 306.5591787493.

The spelling of 28809981 in words is "twenty-eight million, eight hundred nine thousand, nine hundred eighty-one".