21216636100 has 54 divisors (see below), whose sum is σ = 50606089562. Its totient is φ = 7715136000.

The previous prime is 21216636071. The next prime is 21216636139. The reversal of 21216636100 is 163661212.

It can be written as a sum of positive squares in 3 ways, for example, as 210192004 + 21006444096 = 14498^2 + 144936^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 864621 + ... + 888820.

Almost surely, 2^21216636100 is an apocalyptic number.

21216636100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21216636100 is an abundant number, since it is smaller than the sum of its proper divisors (29389453462).

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

21216636100 is a wasteful number, since it uses less digits than its factorization.

21216636100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1753477 (or 1753459 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The spelling of 21216636100 in words is "twenty-one billion, two hundred sixteen million, six hundred thirty-six thousand, one hundred".