21820797 has 12 divisors (see below), whose sum is σ = 33178080. Its totient is φ = 13781448.

The previous prime is 21820793. The next prime is 21820811. The reversal of 21820797 is 79702812.

It is not a de Polignac number, because 21820797 - 2² = 21820793 is a prime.

It is a super-2 number, since 2×21820797² = 952294363430418, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820793) 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, 63633 + ... + 63974.

It is an arithmetic number, because the mean of its divisors is an integer number (2764840).

Almost surely, 2^21820797 is an apocalyptic number.

It is an amenable number.

21820797 is a deficient number, since it is larger than the sum of its proper divisors (11357283).

21820797 is a wasteful number, since it uses less digits than its factorization.

21820797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127632 (or 127629 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 21820797 is about 4671.2735950702. The cubic root of 21820797 is about 279.4410490504.

The spelling of 21820797 in words is "twenty-one million, eight hundred twenty thousand, seven hundred ninety-seven".