21075091 has 2 divisors, whose sum is σ = 21075092. Its totient is φ = 21075090.

The previous prime is 21075077. The next prime is 21075113. The reversal of 21075091 is 19057012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21075091 - 2⁵ = 21075059 is a prime.

It is not a weakly prime, because it can be changed into another prime (21075011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10537545 + 10537546.

It is an arithmetic number, because the mean of its divisors is an integer number (10537546).

Almost surely, 2^21075091 is an apocalyptic number.

21075091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21075091 is an equidigital number, since it uses as much as digits as its factorization.

21075091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 630, while the sum is 25.

The square root of 21075091 is about 4590.7614836757. The cubic root of 21075091 is about 276.2208683271.

The spelling of 21075091 in words is "twenty-one million, seventy-five thousand, ninety-one".