20767531721 has 8 divisors (see below), whose sum is σ = 21990428064. Its totient is φ = 19544777280.

The previous prime is 20767531709. The next prime is 20767531723. The reversal of 20767531721 is 12713576702.

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 20767531721 - 2²² = 20763337417 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20767531723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 479786 + ... + 521276.

It is an arithmetic number, because the mean of its divisors is an integer number (2748803508).

Almost surely, 2^20767531721 is an apocalyptic number.

It is an amenable number.

20767531721 is a deficient number, since it is larger than the sum of its proper divisors (1222896343).

20767531721 is a wasteful number, since it uses less digits than its factorization.

20767531721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70951.

The product of its (nonzero) digits is 123480, while the sum is 41.

The spelling of 20767531721 in words is "twenty billion, seven hundred sixty-seven million, five hundred thirty-one thousand, seven hundred twenty-one".