21955567 has 2 divisors, whose sum is σ = 21955568. Its totient is φ = 21955566.

The previous prime is 21955559. The next prime is 21955573. The reversal of 21955567 is 76555912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21955567 - 2³ = 21955559 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21955067) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10977783 + 10977784.

It is an arithmetic number, because the mean of its divisors is an integer number (10977784).

Almost surely, 2^21955567 is an apocalyptic number.

21955567 is a deficient number, since it is larger than the sum of its proper divisors (1).

21955567 is an equidigital number, since it uses as much as digits as its factorization.

21955567 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 94500, while the sum is 40.

The square root of 21955567 is about 4685.6767920974. The cubic root of 21955567 is about 280.0151649950.

It can be divided in two parts, 21955 and 567, that added together give a palindrome (22522).

The spelling of 21955567 in words is "twenty-one million, nine hundred fifty-five thousand, five hundred sixty-seven".