21357897924 has 24 divisors (see below), whose sum is σ = 54365558688. Its totient is φ = 6472090240.

The previous prime is 21357897923. The next prime is 21357897947. The reversal of 21357897924 is 42979875312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21357897923) 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, 80900997 + ... + 80901260.

It is an arithmetic number, because the mean of its divisors is an integer number (2265231612).

Almost surely, 2^21357897924 is an apocalyptic number.

It is an amenable number.

21357897924 is an abundant number, since it is smaller than the sum of its proper divisors (33007660764).

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

21357897924 is a wasteful number, since it uses less digits than its factorization.

21357897924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161802275 (or 161802273 counting only the distinct ones).

The product of its digits is 7620480, while the sum is 57.

The spelling of 21357897924 in words is "twenty-one billion, three hundred fifty-seven million, eight hundred ninety-seven thousand, nine hundred twenty-four".