21531102455240 has 64 divisors (see below), whose sum is σ = 55396850140800. Its totient is φ = 7377937855488.

The previous prime is 21531102455227. The next prime is 21531102455273. The reversal of 21531102455240 is 4255420113512.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 21531102455240.

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, 21139130 + ... + 22134249.

It is an arithmetic number, because the mean of its divisors is an integer number (865575783450).

Almost surely, 2^{21531102455240} is an apocalyptic number.

21531102455240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21531102455240 is an abundant number, since it is smaller than the sum of its proper divisors (33865747685560).

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

21531102455240 is a wasteful number, since it uses less digits than its factorization.

21531102455240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43275174 (or 43275170 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 35.

Adding to 21531102455240 its reverse (4255420113512), we get a palindrome (25786522568752).

The spelling of 21531102455240 in words is "twenty-one trillion, five hundred thirty-one billion, one hundred two million, four hundred fifty-five thousand, two hundred forty".