21311215400 has 48 divisors (see below), whose sum is σ = 49614382140. Its totient is φ = 8513164800.

The previous prime is 21311215397. The next prime is 21311215421. The reversal of 21311215400 is 451211312.

It can be written as a sum of positive squares in 6 ways, for example, as 3044611684 + 18266603716 = 55178^2 + 135154^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 81020 + ... + 221780.

Almost surely, 2^21311215400 is an apocalyptic number.

21311215400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21311215400 is an abundant number, since it is smaller than the sum of its proper divisors (28303166740).

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

21311215400 is a wasteful number, since it uses less digits than its factorization.

21311215400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141534 (or 141525 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 20.

Adding to 21311215400 its reverse (451211312), we get a palindrome (21762426712).

The spelling of 21311215400 in words is "twenty-one billion, three hundred eleven million, two hundred fifteen thousand, four hundred".