21162791 has 8 divisors (see below), whose sum is σ = 23165184. Its totient is φ = 19213920.

The previous prime is 21162787. The next prime is 21162793. The reversal of 21162791 is 19726112.

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

It is a cyclic number.

It is not a de Polignac number, because 21162791 - 2² = 21162787 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21162793) 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 in 7 ways as a sum of consecutive naturals, for example, 12551 + ... + 14136.

It is an arithmetic number, because the mean of its divisors is an integer number (2895648).

Almost surely, 2^21162791 is an apocalyptic number.

21162791 is a deficient number, since it is larger than the sum of its proper divisors (2002393).

21162791 is a wasteful number, since it uses less digits than its factorization.

21162791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26761.

The product of its digits is 1512, while the sum is 29.

The square root of 21162791 is about 4600.3033595623. The cubic root of 21162791 is about 276.6034850322.

The spelling of 21162791 in words is "twenty-one million, one hundred sixty-two thousand, seven hundred ninety-one".