20981817 has 12 divisors (see below), whose sum is σ = 30354480. Its totient is φ = 13966008.

The previous prime is 20981803. The next prime is 20981827. The reversal of 20981817 is 71818902.

It is not a de Polignac number, because 20981817 - 2⁴ = 20981801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20981827) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6034 + ... + 8852.

It is an arithmetic number, because the mean of its divisors is an integer number (2529540).

Almost surely, 2^20981817 is an apocalyptic number.

It is an amenable number.

20981817 is a deficient number, since it is larger than the sum of its proper divisors (9372663).

20981817 is a wasteful number, since it uses less digits than its factorization.

20981817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3652 (or 3649 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 20981817 is about 4580.5913373712. The cubic root of 20981817 is about 275.8127668381.

The spelling of 20981817 in words is "twenty million, nine hundred eighty-one thousand, eight hundred seventeen".