21976091 has 2 divisors, whose sum is σ = 21976092. Its totient is φ = 21976090.

The previous prime is 21976081. The next prime is 21976093. The reversal of 21976091 is 19067912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21976091 is a prime.

Together with 21976093, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1387844 and since 21976091 and 1387844 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21976093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10988045 + 10988046.

It is an arithmetic number, because the mean of its divisors is an integer number (10988046).

Almost surely, 2^21976091 is an apocalyptic number.

21976091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21976091 is an equidigital number, since it uses as much as digits as its factorization.

21976091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 21976091 is about 4687.8663590166. The cubic root of 21976091 is about 280.1023902745.

The spelling of 21976091 in words is "twenty-one million, nine hundred seventy-six thousand, ninety-one".