21026091 has 8 divisors (see below), whose sum is σ = 28939264. Its totient is φ = 13565160.

The previous prime is 21026081. The next prime is 21026099. The reversal of 21026091 is 19062012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21026091 - 2²³ = 12637483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21026099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 112951 + ... + 113136.

It is an arithmetic number, because the mean of its divisors is an integer number (3617408).

Almost surely, 2^21026091 is an apocalyptic number.

21026091 is a deficient number, since it is larger than the sum of its proper divisors (7913173).

21026091 is a wasteful number, since it uses less digits than its factorization.

21026091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226121.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 21026091 is about 4585.4215727673. The cubic root of 21026091 is about 276.0066292254.

The spelling of 21026091 in words is "twenty-one million, twenty-six thousand, ninety-one".