21253442921 has 8 divisors (see below), whose sum is σ = 22794160320. Its totient is φ = 19754937072.

The previous prime is 21253442879. The next prime is 21253442927. The reversal of 21253442921 is 12924435212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21253442921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21253442927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10551845 + ... + 10553858.

It is an arithmetic number, because the mean of its divisors is an integer number (2849270040).

Almost surely, 2^21253442921 is an apocalyptic number.

It is an amenable number.

21253442921 is a deficient number, since it is larger than the sum of its proper divisors (1540717399).

21253442921 is a wasteful number, since it uses less digits than its factorization.

21253442921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21105775.

The product of its digits is 34560, while the sum is 35.

The spelling of 21253442921 in words is "twenty-one billion, two hundred fifty-three million, four hundred forty-two thousand, nine hundred twenty-one".