20980981 has 4 divisors (see below), whose sum is σ = 23978272. Its totient is φ = 17983692.

The previous prime is 20980957. The next prime is 20980987. The reversal of 20980981 is 18908902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20980981 - 2⁹ = 20980469 is a prime.

It is a super-2 number, since 2×20980981² = 880403127444722, which contains 22 as substring.

It is the 4581-st Hogben number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20980981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20980987) by changing a digit.

It is a nontrivial repunit in base 4580.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1498635 + ... + 1498648.

It is an arithmetic number, because the mean of its divisors is an integer number (5994568).

Almost surely, 2^20980981 is an apocalyptic number.

It is an amenable number.

20980981 is a deficient number, since it is larger than the sum of its proper divisors (2997291).

20980981 is an equidigital number, since it uses as much as digits as its factorization.

20980981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2997290.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 20980981 is about 4580.5000818688. The cubic root of 20980981 is about 275.8091036261.

The spelling of 20980981 in words is "twenty million, nine hundred eighty thousand, nine hundred eighty-one".