21511982 has 4 divisors (see below), whose sum is σ = 32267976. Its totient is φ = 10755990.

The previous prime is 21511979. The next prime is 21511991. The reversal of 21511982 is 28911512.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5377994 + ... + 5377997.

It is an arithmetic number, because the mean of its divisors is an integer number (8066994).

Almost surely, 2^21511982 is an apocalyptic number.

21511982 is a deficient number, since it is larger than the sum of its proper divisors (10755994).

21511982 is a wasteful number, since it uses less digits than its factorization.

21511982 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10755993.

The product of its digits is 1440, while the sum is 29.

The square root of 21511982 is about 4638.1011200706. The cubic root of 21511982 is about 278.1165341361.

The spelling of 21511982 in words is "twenty-one million, five hundred eleven thousand, nine hundred eighty-two".