20992581 has 16 divisors (see below), whose sum is σ = 31177920. Its totient is φ = 13960080.

The previous prime is 20992567. The next prime is 20992589. The reversal of 20992581 is 18529902.

It is not a de Polignac number, because 20992581 - 2⁷ = 20992453 is a prime.

It is a super-2 number, since 2×20992581² = 881376914083122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20992589) 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, 14511 + ... + 15891.

It is an arithmetic number, because the mean of its divisors is an integer number (1948620).

Almost surely, 2^20992581 is an apocalyptic number.

It is an amenable number.

20992581 is a deficient number, since it is larger than the sum of its proper divisors (10185339).

20992581 is a wasteful number, since it uses less digits than its factorization.

20992581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1953 (or 1947 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 20992581 is about 4581.7661441850. The cubic root of 20992581 is about 275.8599241947.

The spelling of 20992581 in words is "twenty million, nine hundred ninety-two thousand, five hundred eighty-one".