21055205136 has 240 divisors, whose sum is σ = 65464381440. Its totient is φ = 5810837760.

The previous prime is 21055205107. The next prime is 21055205147. The reversal of 21055205136 is 63150255012.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8731771 + ... + 8734181.

It is an arithmetic number, because the mean of its divisors is an integer number (272768256).

Almost surely, 2^21055205136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21055205136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32732190720).

21055205136 is an abundant number, since it is smaller than the sum of its proper divisors (44409176304).

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

21055205136 is a wasteful number, since it uses less digits than its factorization.

21055205136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2562 (or 2549 counting only the distinct ones).

The product of its (nonzero) digits is 9000, while the sum is 30.

The spelling of 21055205136 in words is "twenty-one billion, fifty-five million, two hundred five thousand, one hundred thirty-six".