21262130640 has 280 divisors, whose sum is σ = 74541244680. Its totient is φ = 5637537792.

The previous prime is 21262130629. The next prime is 21262130657. The reversal of 21262130640 is 4603126212.

21262130640 is a `hidden beast` number, since 2 + 1 + 2 + 6 + 2 + 13 + 0 + 640 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 660695616 + 20601435024 = 25704^2 + 143532^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 11254816 + ... + 11256704.

It is an arithmetic number, because the mean of its divisors is an integer number (266218731).

Almost surely, 2^21262130640 is an apocalyptic number.

21262130640 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 21262130640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37270622340).

21262130640 is an abundant number, since it is smaller than the sum of its proper divisors (53279114040).

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

21262130640 is a wasteful number, since it uses less digits than its factorization.

21262130640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2113 (or 2092 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

Adding to 21262130640 its reverse (4603126212), we get a palindrome (25865256852).

The spelling of 21262130640 in words is "twenty-one billion, two hundred sixty-two million, one hundred thirty thousand, six hundred forty".