21535091 has 2 divisors, whose sum is σ = 21535092. Its totient is φ = 21535090.

The previous prime is 21535027. The next prime is 21535093. The reversal of 21535091 is 19053512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21535091 - 2⁶ = 21535027 is a prime.

Together with 21535093, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1361645 and since 21535091 and 1361645 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21535091.

It is not a weakly prime, because it can be changed into another prime (21535093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10767545 + 10767546.

It is an arithmetic number, because the mean of its divisors is an integer number (10767546).

Almost surely, 2^21535091 is an apocalyptic number.

21535091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21535091 is an equidigital number, since it uses as much as digits as its factorization.

21535091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1350, while the sum is 26.

The square root of 21535091 is about 4640.5916648634. The cubic root of 21535091 is about 278.2160863296.

The spelling of 21535091 in words is "twenty-one million, five hundred thirty-five thousand, ninety-one".