21621531101000 has 128 divisors (see below), whose sum is σ = 51555115029600. Its totient is φ = 8484423500800.

The previous prime is 21621531100993. The next prime is 21621531101011. The reversal of 21621531101000 is 10113512612.

It can be written as a sum of positive squares in 16 ways, for example, as 2062794724 + 21619468306276 = 45418^2 + 4649674^2 .

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, 575190206 + ... + 575227794.

Almost surely, 2^{21621531101000} is an apocalyptic number.

21621531101000 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 21621531101000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25777557514800).

21621531101000 is an abundant number, since it is smaller than the sum of its proper divisors (29933583928600).

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

21621531101000 is a wasteful number, since it uses less digits than its factorization.

21621531101000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48516 (or 48502 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 23.

Adding to 21621531101000 its reverse (10113512612), we get a palindrome (21631644613612).

The spelling of 21621531101000 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred thirty-one million, one hundred one thousand".