21265284240 has 160 divisors (see below), whose sum is σ = 73429228800. Its totient is φ = 5656642560.

The previous prime is 21265284233. The next prime is 21265284277. The reversal of 21265284240 is 4248256212.

21265284240 is a `hidden beast` number, since 2 + 126 + 528 + 4 + 2 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21265284195 and 21265284204.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 871405 + ... + 895475.

It is an arithmetic number, because the mean of its divisors is an integer number (458932680).

Almost surely, 2^21265284240 is an apocalyptic number.

21265284240 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 21265284240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36714614400).

21265284240 is an abundant number, since it is smaller than the sum of its proper divisors (52163944560).

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

21265284240 is a wasteful number, since it uses less digits than its factorization.

21265284240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24502 (or 24490 counting only the distinct ones).

The product of its (nonzero) digits is 61440, while the sum is 36.

The spelling of 21265284240 in words is "twenty-one billion, two hundred sixty-five million, two hundred eighty-four thousand, two hundred forty".