21255120420 has 48 divisors (see below), whose sum is σ = 59583444480. Its totient is φ = 5661450496.

The previous prime is 21255120413. The next prime is 21255120427. The reversal of 21255120420 is 2402155212.

It is an interprime number because it is at equal distance from previous prime (21255120413) and next prime (21255120427).

It is not an unprimeable number, because it can be changed into a prime (21255120427) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 153465 + ... + 257024.

It is an arithmetic number, because the mean of its divisors is an integer number (1241321760).

Almost surely, 2^21255120420 is an apocalyptic number.

21255120420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21255120420 is an abundant number, since it is smaller than the sum of its proper divisors (38328324060).

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

21255120420 is a wasteful number, since it uses less digits than its factorization.

21255120420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411364 (or 411362 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 24.

Adding to 21255120420 its reverse (2402155212), we get a palindrome (23657275632).

The spelling of 21255120420 in words is "twenty-one billion, two hundred fifty-five million, one hundred twenty thousand, four hundred twenty".