21856577730 has 128 divisors (see below), whose sum is σ = 57610828800. Its totient is φ = 5273942784.

The previous prime is 21856577711. The next prime is 21856577741. The reversal of 21856577730 is 3777565812.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 9640057 + ... + 9642323.

It is an arithmetic number, because the mean of its divisors is an integer number (450084600).

Almost surely, 2^21856577730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21856577730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28805414400).

21856577730 is an abundant number, since it is smaller than the sum of its proper divisors (35754251070).

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

21856577730 is a wasteful number, since it uses less digits than its factorization.

21856577730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2768.

The product of its (nonzero) digits is 2469600, while the sum is 51.

The spelling of 21856577730 in words is "twenty-one billion, eight hundred fifty-six million, five hundred seventy-seven thousand, seven hundred thirty".