17978689663431 has 32 divisors (see below), whose sum is σ = 28185886038528. Its totient is φ = 9981567636480.

The previous prime is 17978689663427. The next prime is 17978689663439. The reversal of 17978689663431 is 13436698687971.

It is not a de Polignac number, because 17978689663431 - 2² = 17978689663427 is a prime.

It is a super-2 number, since 2×17978689663431² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (17978689663439) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 87418050 + ... + 87623471.

It is an arithmetic number, because the mean of its divisors is an integer number (880808938704).

Almost surely, 2^{17978689663431} is an apocalyptic number.

17978689663431 is a deficient number, since it is larger than the sum of its proper divisors (10207196375097).

17978689663431 is a wasteful number, since it uses less digits than its factorization.

17978689663431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175041671.

The product of its digits is 1975228416, while the sum is 78.

The spelling of 17978689663431 in words is "seventeen trillion, nine hundred seventy-eight billion, six hundred eighty-nine million, six hundred sixty-three thousand, four hundred thirty-one".