21221305404 has 24 divisors (see below), whose sum is σ = 53325331920. Its totient is φ = 6529632384.

The previous prime is 21221305381. The next prime is 21221305421. The reversal of 21221305404 is 40450312212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68016849 + ... + 68017160.

It is an arithmetic number, because the mean of its divisors is an integer number (2221888830).

Almost surely, 2^21221305404 is an apocalyptic number.

It is an amenable number.

21221305404 is an abundant number, since it is smaller than the sum of its proper divisors (32104026516).

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

21221305404 is a wasteful number, since it uses less digits than its factorization.

21221305404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136034029 (or 136034027 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

Adding to 21221305404 its reverse (40450312212), we get a palindrome (61671617616).

The spelling of 21221305404 in words is "twenty-one billion, two hundred twenty-one million, three hundred five thousand, four hundred four".