21521116100 has 72 divisors (see below), whose sum is σ = 53161472448. Its totient is φ = 7485596800.

The previous prime is 21521116093. The next prime is 21521116103. The reversal of 21521116100 is 161112512.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21521116103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 400019 + ... + 450618.

It is an arithmetic number, because the mean of its divisors is an integer number (738353784).

Almost surely, 2^21521116100 is an apocalyptic number.

21521116100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21521116100 is an abundant number, since it is smaller than the sum of its proper divisors (31640356348).

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

21521116100 is a wasteful number, since it uses less digits than its factorization.

21521116100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850685 (or 850678 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 20.

Adding to 21521116100 its reverse (161112512), we get a palindrome (21682228612).

The spelling of 21521116100 in words is "twenty-one billion, five hundred twenty-one million, one hundred sixteen thousand, one hundred".