21005660015250 has 128 divisors (see below), whose sum is σ = 53231674728960. Its totient is φ = 5516474976000.

The previous prime is 21005660015239. The next prime is 21005660015269. The reversal of 21005660015250 is 5251006650012.

It is a Curzon number.

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, 13231096 + ... + 14733404.

It is an arithmetic number, because the mean of its divisors is an integer number (415872458820).

Almost surely, 2^{21005660015250} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21005660015250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26615837364480).

21005660015250 is an abundant number, since it is smaller than the sum of its proper divisors (32226014713710).

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

21005660015250 is a wasteful number, since it uses less digits than its factorization.

21005660015250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1502613 (or 1502603 counting only the distinct ones).

The product of its (nonzero) digits is 18000, while the sum is 33.

Adding to 21005660015250 its reverse (5251006650012), we get a palindrome (26256666665262).

The spelling of 21005660015250 in words is "twenty-one trillion, five billion, six hundred sixty million, fifteen thousand, two hundred fifty".