21968001729 has 24 divisors (see below), whose sum is σ = 32833056360. Its totient is φ = 14137175808.

The previous prime is 21968001721. The next prime is 21968001743. The reversal of 21968001729 is 92710086912.

It can be written as a sum of positive squares in 4 ways, for example, as 13195806129 + 8772195600 = 114873^2 + 93660^2 .

It is not a de Polignac number, because 21968001729 - 2³ = 21968001721 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21968001721) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1945869 + ... + 1957125.

It is an arithmetic number, because the mean of its divisors is an integer number (1368044015).

Almost surely, 2^21968001729 is an apocalyptic number.

21968001729 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21968001729 is a deficient number, since it is larger than the sum of its proper divisors (10865054631).

21968001729 is a wasteful number, since it uses less digits than its factorization.

21968001729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18769 (or 18766 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The spelling of 21968001729 in words is "twenty-one billion, nine hundred sixty-eight million, one thousand, seven hundred twenty-nine".