21195091 has 2 divisors, whose sum is σ = 21195092. Its totient is φ = 21195090.

The previous prime is 21195077. The next prime is 21195113. The reversal of 21195091 is 19059112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21195091 - 2⁵ = 21195059 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21195061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10597545 + 10597546.

It is an arithmetic number, because the mean of its divisors is an integer number (10597546).

Almost surely, 2^21195091 is an apocalyptic number.

21195091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21195091 is an equidigital number, since it uses as much as digits as its factorization.

21195091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 810, while the sum is 28.

The square root of 21195091 is about 4603.8126590903. The cubic root of 21195091 is about 276.7441367867.

It can be divided in two parts, 21 and 195091, that added together give a cube (195112 = 58³).

The spelling of 21195091 in words is "twenty-one million, one hundred ninety-five thousand, ninety-one".