21255870240 has 144 divisors (see below), whose sum is σ = 79129866816. Its totient is φ = 5152934400.

The previous prime is 21255870227. The next prime is 21255870257. The reversal of 21255870240 is 4207855212.

It is a happy number.

21255870240 is a `hidden beast` number, since 2 + 12 + 558 + 70 + 24 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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 = 21255870195 and 21255870204.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 655116 + ... + 686795.

It is an arithmetic number, because the mean of its divisors is an integer number (549512964).

Almost surely, 2^21255870240 is an apocalyptic number.

21255870240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21255870240 is an abundant number, since it is smaller than the sum of its proper divisors (57873996576).

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

21255870240 is a wasteful number, since it uses less digits than its factorization.

21255870240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341943 (or 1341932 counting only the distinct ones).

The product of its (nonzero) digits is 44800, while the sum is 36.

The spelling of 21255870240 in words is "twenty-one billion, two hundred fifty-five million, eight hundred seventy thousand, two hundred forty".