21431426165 has 8 divisors (see below), whose sum is σ = 25721428920. Its totient is φ = 17142662592.

The previous prime is 21431426161. The next prime is 21431426171. The reversal of 21431426165 is 56162413412.

It can be written as a sum of positive squares in 4 ways, for example, as 2807092324 + 18624333841 = 52982^2 + 136471^2 .

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 21431426165 - 2² = 21431426161 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431426161) 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, 271310 + ... + 341279.

It is an arithmetic number, because the mean of its divisors is an integer number (3215178615).

Almost surely, 2^21431426165 is an apocalyptic number.

It is an amenable number.

21431426165 is a deficient number, since it is larger than the sum of its proper divisors (4290002755).

21431426165 is an equidigital number, since it uses as much as digits as its factorization.

21431426165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 619591.

The product of its digits is 34560, while the sum is 35.

Adding to 21431426165 its reverse (56162413412), we get a palindrome (77593839577).

The spelling of 21431426165 in words is "twenty-one billion, four hundred thirty-one million, four hundred twenty-six thousand, one hundred sixty-five".