15721721458761 has 8 divisors (see below), whose sum is σ = 22195371471264. Its totient is φ = 9864609542720.

The previous prime is 15721721458757. The next prime is 15721721458763. The reversal of 15721721458761 is 16785412712751.

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

It is a cyclic number.

It is not a de Polignac number, because 15721721458761 - 2² = 15721721458757 is a prime.

It is a super-2 number, since 2×15721721458761² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (15721721458763) 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, 154134524055 + ... + 154134524156.

It is an arithmetic number, because the mean of its divisors is an integer number (2774421433908).

Almost surely, 2^{15721721458761} is an apocalyptic number.

It is an amenable number.

15721721458761 is a deficient number, since it is larger than the sum of its proper divisors (6473650012503).

15721721458761 is a wasteful number, since it uses less digits than its factorization.

15721721458761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308269048231.

The product of its digits is 6585600, while the sum is 57.

The spelling of 15721721458761 in words is "fifteen trillion, seven hundred twenty-one billion, seven hundred twenty-one million, four hundred fifty-eight thousand, seven hundred sixty-one".