21712051721 has 8 divisors (see below), whose sum is σ = 22993920000. Its totient is φ = 20430704448.

The previous prime is 21712051703. The next prime is 21712051759. The reversal of 21712051721 is 12715021712.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21712051721 - 2¹⁴ = 21712035337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21712051321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42761 + ... + 212726.

It is an arithmetic number, because the mean of its divisors is an integer number (2874240000).

Almost surely, 2^21712051721 is an apocalyptic number.

It is an amenable number.

21712051721 is a deficient number, since it is larger than the sum of its proper divisors (1281868279).

21712051721 is a wasteful number, since it uses less digits than its factorization.

21712051721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260503.

The product of its (nonzero) digits is 1960, while the sum is 29.

The spelling of 21712051721 in words is "twenty-one billion, seven hundred twelve million, fifty-one thousand, seven hundred twenty-one".