21131100240 has 80 divisors (see below), whose sum is σ = 65529734400. Its totient is φ = 5632953856.

The previous prime is 21131100217. The next prime is 21131100251. The reversal of 21131100240 is 4200113112.

It is a tau number, because it is divible by the number of its divisors (80).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 734446 + ... + 762674.

It is an arithmetic number, because the mean of its divisors is an integer number (819121680).

Almost surely, 2^21131100240 is an apocalyptic number.

21131100240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21131100240 is an abundant number, since it is smaller than the sum of its proper divisors (44398634160).

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

21131100240 is a wasteful number, since it uses less digits than its factorization.

21131100240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31364 (or 31358 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21131100240 its reverse (4200113112), we get a palindrome (25331213352).

The spelling of 21131100240 in words is "twenty-one billion, one hundred thirty-one million, one hundred thousand, two hundred forty".