21943681956 has 81 divisors (see below), whose sum is σ = 64543174059. Its totient is φ = 6267845808.

The previous prime is 21943681943. The next prime is 21943681961. The reversal of 21943681956 is 65918634912.

The square root of 21943681956 is 148134.

It is a perfect power (a square), and thus also a powerful number.

21943681956 is a `hidden beast` number, since 2 + 1 + 94 + 368 + 195 + 6 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 6219865 + ... + 6223391.

Almost surely, 2^21943681956 is an apocalyptic number.

21943681956 is the 148134-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21943681956

21943681956 is an abundant number, since it is smaller than the sum of its proper divisors (42599492103).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21943681956 is an equidigital number, since it uses as much as digits as its factorization.

21943681956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7078 (or 3539 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 54.

It can be divided in two parts, 2194368 and 1956, that added together give a square (2196324 = 1482²).

The spelling of 21943681956 in words is "twenty-one billion, nine hundred forty-three million, six hundred eighty-one thousand, nine hundred fifty-six".