21240820900 has 72 divisors (see below), whose sum is σ = 51349916520. Its totient is φ = 7572311040.

The previous prime is 21240820891. The next prime is 21240820903. The reversal of 21240820900 is 902804212.

It can be written as a sum of positive squares in 12 ways, for example, as 13949027236 + 7291793664 = 118106^2 + 85392^2 .

It is not an unprimeable number, because it can be changed into a prime (21240820903) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 244009 + ... + 319408.

It is an arithmetic number, because the mean of its divisors is an integer number (713193285).

Almost surely, 2^21240820900 is an apocalyptic number.

21240820900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21240820900 is an abundant number, since it is smaller than the sum of its proper divisors (30109095620).

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

21240820900 is a wasteful number, since it uses less digits than its factorization.

21240820900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563473 (or 563466 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The spelling of 21240820900 in words is "twenty-one billion, two hundred forty million, eight hundred twenty thousand, nine hundred".