21240200400 has 60 divisors (see below), whose sum is σ = 68039445792. Its totient is φ = 5664053120.

The previous prime is 21240200389. The next prime is 21240200413. The reversal of 21240200400 is 400204212.

It is a tau number, because it is divible by the number of its divisors (60).

It is a super-2 number, since 2×21240200400² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21240200400.

It is a congruent number.

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, 8848884 + ... + 8851283.

Almost surely, 2^21240200400 is an apocalyptic number.

21240200400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21240200400 is an abundant number, since it is smaller than the sum of its proper divisors (46799245392).

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

21240200400 is a wasteful number, since it uses less digits than its factorization.

21240200400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17700188 (or 17700177 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 15.

Adding to 21240200400 its reverse (400204212), we get a palindrome (21640404612).

The spelling of 21240200400 in words is "twenty-one billion, two hundred forty million, two hundred thousand, four hundred".