21513023100 has 108 divisors (see below), whose sum is σ = 67625576200. Its totient is φ = 5720284800.

The previous prime is 21513023093. The next prime is 21513023123. The reversal of 21513023100 is 132031512.

21513023100 is a `hidden beast` number, since 2 + 1 + 51 + 302 + 310 + 0 = 666.

It is a super-2 number, since 2×21513023100² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 279855 + ... + 348345.

Almost surely, 2^21513023100 is an apocalyptic number.

21513023100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21513023100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33812788100).

21513023100 is an abundant number, since it is smaller than the sum of its proper divisors (46112553100).

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

21513023100 is a wasteful number, since it uses less digits than its factorization.

21513023100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68860 (or 68850 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

Adding to 21513023100 its reverse (132031512), we get a palindrome (21645054612).

The spelling of 21513023100 in words is "twenty-one billion, five hundred thirteen million, twenty-three thousand, one hundred".