21205237700 has 18 divisors (see below), whose sum is σ = 46015366026. Its totient is φ = 8482095040.

The previous prime is 21205237607. The next prime is 21205237733. The reversal of 21205237700 is 773250212.

It can be written as a sum of positive squares in 3 ways, for example, as 187197124 + 21018040576 = 13682^2 + 144976^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 106026089 + ... + 106026288.

Almost surely, 2^21205237700 is an apocalyptic number.

21205237700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21205237700 is an abundant number, since it is smaller than the sum of its proper divisors (24810128326).

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

21205237700 is a wasteful number, since it uses less digits than its factorization.

21205237700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212052391 (or 212052384 counting only the distinct ones).

The product of its (nonzero) digits is 5880, while the sum is 29.

Adding to 21205237700 its reverse (773250212), we get a palindrome (21978487912).

The spelling of 21205237700 in words is "twenty-one billion, two hundred five million, two hundred thirty-seven thousand, seven hundred".