21617129381 has 8 divisors (see below), whose sum is σ = 22388016384. Its totient is φ = 20859198640.

The previous prime is 21617129363. The next prime is 21617129389. The reversal of 21617129381 is 18392171612.

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 21617129381 - 2²² = 21612935077 is a prime.

It is a super-2 number, since 2×21617129381² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21617129389) 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, 3235670 + ... + 3242343.

It is an arithmetic number, because the mean of its divisors is an integer number (2798502048).

Almost surely, 2^21617129381 is an apocalyptic number.

It is an amenable number.

21617129381 is a deficient number, since it is larger than the sum of its proper divisors (770887003).

21617129381 is an equidigital number, since it uses as much as digits as its factorization.

21617129381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6478131.

The product of its digits is 36288, while the sum is 41.

The spelling of 21617129381 in words is "twenty-one billion, six hundred seventeen million, one hundred twenty-nine thousand, three hundred eighty-one".