21691332732428 has 12 divisors (see below), whose sum is σ = 37978559396232. Its totient is φ = 10840315762080.

The previous prime is 21691332732347. The next prime is 21691332732449. The reversal of 21691332732428 is 82423723319612.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21691332732428.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1337641913 + ... + 1337658128.

It is an arithmetic number, because the mean of its divisors is an integer number (3164879949686).

Almost surely, 2^{21691332732428} is an apocalyptic number.

It is an amenable number.

21691332732428 is a deficient number, since it is larger than the sum of its proper divisors (16287226663804).

21691332732428 is a wasteful number, since it uses less digits than its factorization.

21691332732428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2675302072 (or 2675302070 counting only the distinct ones).

The product of its digits is 5225472, while the sum is 53.

The spelling of 21691332732428 in words is "twenty-one trillion, six hundred ninety-one billion, three hundred thirty-two million, seven hundred thirty-two thousand, four hundred twenty-eight".