21957481829 has 4 divisors (see below), whose sum is σ = 22912154976. Its totient is φ = 21002808684.

The previous prime is 21957481813. The next prime is 21957481849. The reversal of 21957481829 is 92818475912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21957481829 - 2⁴ = 21957481813 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 (21957481849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 477336539 + ... + 477336584.

It is an arithmetic number, because the mean of its divisors is an integer number (5728038744).

Almost surely, 2^21957481829 is an apocalyptic number.

It is an amenable number.

21957481829 is a deficient number, since it is larger than the sum of its proper divisors (954673147).

21957481829 is an equidigital number, since it uses as much as digits as its factorization.

21957481829 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 954673146.

The product of its digits is 2903040, while the sum is 56.

The spelling of 21957481829 in words is "twenty-one billion, nine hundred fifty-seven million, four hundred eighty-one thousand, eight hundred twenty-nine".