17983978 has 4 divisors (see below), whose sum is σ = 26975970. Its totient is φ = 8991988.

The previous prime is 17983913. The next prime is 17983981. The reversal of 17983978 is 87938971.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87938971 = 31 ⋅2836741.

It can be written as a sum of positive squares in only one way, i.e., 16949689 + 1034289 = 4117^2 + 1017^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4495993 + ... + 4495996.

Almost surely, 2^17983978 is an apocalyptic number.

17983978 is a deficient number, since it is larger than the sum of its proper divisors (8991992).

17983978 is an equidigital number, since it uses as much as digits as its factorization.

17983978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8991991.

The product of its digits is 762048, while the sum is 52.

The square root of 17983978 is about 4240.7520559448. The cubic root of 17983978 is about 261.9963579705.

It can be divided in two parts, 1798 and 3978, that added together give a square (5776 = 76²).

The spelling of 17983978 in words is "seventeen million, nine hundred eighty-three thousand, nine hundred seventy-eight".