21721477204 has 48 divisors (see below), whose sum is σ = 43593209856. Its totient is φ = 9277077600.

The previous prime is 21721477189. The next prime is 21721477223. The reversal of 21721477204 is 40277412712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14374809 + ... + 14376319.

It is an arithmetic number, because the mean of its divisors is an integer number (908191872).

Almost surely, 2^21721477204 is an apocalyptic number.

It is an amenable number.

21721477204 is an abundant number, since it is smaller than the sum of its proper divisors (21871732652).

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

21721477204 is a wasteful number, since it uses less digits than its factorization.

21721477204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2956 (or 2954 counting only the distinct ones).

The product of its (nonzero) digits is 43904, while the sum is 37.

Adding to 21721477204 its reverse (40277412712), we get a palindrome (61998889916).

The spelling of 21721477204 in words is "twenty-one billion, seven hundred twenty-one million, four hundred seventy-seven thousand, two hundred four".