21209056572 has 48 divisors (see below), whose sum is σ = 54871737984. Its totient is φ = 6321624000.

The previous prime is 21209056529. The next prime is 21209056573. The reversal of 21209056572 is 27565090212.

It is a self number, because there is not a number n which added to its sum of digits gives 21209056572.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21209056573) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1308954 + ... + 1325057.

It is an arithmetic number, because the mean of its divisors is an integer number (1143161208).

Almost surely, 2^21209056572 is an apocalyptic number.

21209056572 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21209056572 is an abundant number, since it is smaller than the sum of its proper divisors (33662681412).

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

21209056572 is a wasteful number, since it uses less digits than its factorization.

21209056572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2634090 (or 2634088 counting only the distinct ones).

The product of its (nonzero) digits is 75600, while the sum is 39.

The spelling of 21209056572 in words is "twenty-one billion, two hundred nine million, fifty-six thousand, five hundred seventy-two".