21721270725 has 432 divisors, whose sum is σ = 53771986944. Its totient is φ = 8125920000.

The previous prime is 21721270723. The next prime is 21721270789. The reversal of 21721270725 is 52707212712.

It is a happy number.

It is not a de Polignac number, because 21721270725 - 2¹ = 21721270723 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21721270725.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21721270723) by changing a digit.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 143849400 + ... + 143849550.

It is an arithmetic number, because the mean of its divisors is an integer number (124472192).

Almost surely, 2^21721270725 is an apocalyptic number.

21721270725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21721270725 is an abundant number, since it is smaller than the sum of its proper divisors (32050716219).

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

21721270725 is a wasteful number, since it uses less digits than its factorization.

21721270725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246 (or 219 counting only the distinct ones).

The product of its (nonzero) digits is 27440, while the sum is 36.

The spelling of 21721270725 in words is "twenty-one billion, seven hundred twenty-one million, two hundred seventy thousand, seven hundred twenty-five".