978715981 has 4 divisors (see below), whose sum is σ = 978898464. Its totient is φ = 978533500.

The previous prime is 978715963. The next prime is 978716009. The reversal of 978715981 is 189517879.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 189517879 = 211 ⋅898189.

It is a cyclic number.

It is not a de Polignac number, because 978715981 - 2⁵ = 978715949 is a prime.

It is a super-2 number, since 2×978715981² = 1915769942929584722, which 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 (978715181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82945 + ... + 94006.

It is an arithmetic number, because the mean of its divisors is an integer number (244724616).

Almost surely, 2^978715981 is an apocalyptic number.

It is an amenable number.

978715981 is a deficient number, since it is larger than the sum of its proper divisors (182483).

978715981 is a wasteful number, since it uses less digits than its factorization.

978715981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182482.

The product of its digits is 1270080, while the sum is 55.

The square root of 978715981 is about 31284.4367217951. The cubic root of 978715981 is about 992.8543888592.

The spelling of 978715981 in words is "nine hundred seventy-eight million, seven hundred fifteen thousand, nine hundred eighty-one".