21510056260 has 108 divisors (see below), whose sum is σ = 57757485996. Its totient is φ = 6704396160.

The previous prime is 21510056221. The next prime is 21510056261. The reversal of 21510056260 is 6265001512.

It can be written as a sum of positive squares in 2 ways, for example, as 5834515456 + 15675540804 = 76384^2 + 125202^2 .

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (21510056261) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 27882 + ... + 209278.

It is an arithmetic number, because the mean of its divisors is an integer number (534791537).

Almost surely, 2^21510056260 is an apocalyptic number.

21510056260 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 21510056260, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28878742998).

21510056260 is an abundant number, since it is smaller than the sum of its proper divisors (36247429736).

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

21510056260 is a wasteful number, since it uses less digits than its factorization.

21510056260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181442 (or 181422 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

Adding to 21510056260 its reverse (6265001512), we get a palindrome (27775057772).

The spelling of 21510056260 in words is "twenty-one billion, five hundred ten million, fifty-six thousand, two hundred sixty".