21900691 has 2 divisors, whose sum is σ = 21900692. Its totient is φ = 21900690.

The previous prime is 21900679. The next prime is 21900737. The reversal of 21900691 is 19600912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21900691 - 2¹³ = 21892499 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21900661) 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, 10950345 + 10950346.

It is an arithmetic number, because the mean of its divisors is an integer number (10950346).

Almost surely, 2^21900691 is an apocalyptic number.

21900691 is a deficient number, since it is larger than the sum of its proper divisors (1).

21900691 is an equidigital number, since it uses as much as digits as its factorization.

21900691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 21900691 is about 4679.8174109681. The cubic root of 21900691 is about 279.7816793057.

The spelling of 21900691 in words is "twenty-one million, nine hundred thousand, six hundred ninety-one".