21911797 has 2 divisors, whose sum is σ = 21911798. Its totient is φ = 21911796.

The previous prime is 21911789. The next prime is 21911803. The reversal of 21911797 is 79711912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21911761 + 36 = 4681^2 + 6^2 .

It is a cyclic number.

It is not a de Polignac number, because 21911797 - 2³ = 21911789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21911767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10955898 + 10955899.

It is an arithmetic number, because the mean of its divisors is an integer number (10955899).

Almost surely, 2^21911797 is an apocalyptic number.

It is an amenable number.

21911797 is a deficient number, since it is larger than the sum of its proper divisors (1).

21911797 is an equidigital number, since it uses as much as digits as its factorization.

21911797 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7938, while the sum is 37.

The square root of 21911797 is about 4681.0038453306. The cubic root of 21911797 is about 279.8289644232.

The spelling of 21911797 in words is "twenty-one million, nine hundred eleven thousand, seven hundred ninety-seven".