21121542500 has 60 divisors (see below), whose sum is σ = 47437137132. Its totient is φ = 8220240000.

The previous prime is 21121542461. The next prime is 21121542521. The reversal of 21121542500 is 524512112.

It can be written as a sum of positive squares in 10 ways, for example, as 10012804096 + 11108738404 = 100064^2 + 105398^2 .

It is a super-2 number, since 2×21121542500² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 21671 + ... + 206670.

Almost surely, 2^21121542500 is an apocalyptic number.

21121542500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121542500 is an abundant number, since it is smaller than the sum of its proper divisors (26315594632).

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

21121542500 is a wasteful number, since it uses less digits than its factorization.

21121542500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228402 (or 228385 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 23.

The spelling of 21121542500 in words is "twenty-one billion, one hundred twenty-one million, five hundred forty-two thousand, five hundred".