21321974646 has 24 divisors (see below), whose sum is σ = 52797270864. Its totient is φ = 6091992720.

The previous prime is 21321974593. The next prime is 21321974647. The reversal of 21321974646 is 64647912312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321974647) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 84610885 + ... + 84611136.

It is an arithmetic number, because the mean of its divisors is an integer number (2199886286).

Almost surely, 2^21321974646 is an apocalyptic number.

21321974646 is an abundant number, since it is smaller than the sum of its proper divisors (31475296218).

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

21321974646 is a wasteful number, since it uses less digits than its factorization.

21321974646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169222036 (or 169222033 counting only the distinct ones).

The product of its digits is 435456, while the sum is 45.

The spelling of 21321974646 in words is "twenty-one billion, three hundred twenty-one million, nine hundred seventy-four thousand, six hundred forty-six".