21697744129 has 8 divisors (see below), whose sum is σ = 22327969320. Its totient is φ = 21069824256.

The previous prime is 21697744091. The next prime is 21697744177. The reversal of 21697744129 is 92144779612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 18175084225 + 3522659904 = 134815^2 + 59352^2 .

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 21697744129 - 2¹⁵ = 21697711361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21697744199) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 557224 + ... + 594889.

It is an arithmetic number, because the mean of its divisors is an integer number (2790996165).

Almost surely, 2^21697744129 is an apocalyptic number.

It is an amenable number.

21697744129 is a deficient number, since it is larger than the sum of its proper divisors (630225191).

21697744129 is a wasteful number, since it uses less digits than its factorization.

21697744129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1152659.

The product of its digits is 1524096, while the sum is 52.

The spelling of 21697744129 in words is "twenty-one billion, six hundred ninety-seven million, seven hundred forty-four thousand, one hundred twenty-nine".