21491356 has 24 divisors (see below), whose sum is σ = 40078080. Its totient is φ = 10054512.

The previous prime is 21491297. The next prime is 21491369. The reversal of 21491356 is 65319412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4605 + ... + 8011.

It is an arithmetic number, because the mean of its divisors is an integer number (1669920).

Almost surely, 2^21491356 is an apocalyptic number.

It is an amenable number.

21491356 is a deficient number, since it is larger than the sum of its proper divisors (18586724).

21491356 is a wasteful number, since it uses less digits than its factorization.

21491356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3513 (or 3511 counting only the distinct ones).

The product of its digits is 6480, while the sum is 31.

The square root of 21491356 is about 4635.8770475499. The cubic root of 21491356 is about 278.0276183247.

The spelling of 21491356 in words is "twenty-one million, four hundred ninety-one thousand, three hundred fifty-six".