78994981 has 4 divisors (see below), whose sum is σ = 85071532. Its totient is φ = 72918432.

The previous prime is 78994969. The next prime is 78995003. The reversal of 78994981 is 18949987.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40132225 + 38862756 = 6335^2 + 6234^2 .

It is a cyclic number.

It is not a de Polignac number, because 78994981 - 2²¹ = 76897829 is a prime.

It is a super-2 number, since 2×78994981² = 12480414046380722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78994081) 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, 3038256 + ... + 3038281.

It is an arithmetic number, because the mean of its divisors is an integer number (21267883).

Almost surely, 2^78994981 is an apocalyptic number.

It is an amenable number.

78994981 is a deficient number, since it is larger than the sum of its proper divisors (6076551).

78994981 is a wasteful number, since it uses less digits than its factorization.

78994981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6076550.

The product of its digits is 1306368, while the sum is 55.

The square root of 78994981 is about 8887.9120720223. The cubic root of 78994981 is about 429.0749557051.

It can be divided in two parts, 7899 and 4981, that added together give a triangular number (12880 = T₁₆₀).

The spelling of 78994981 in words is "seventy-eight million, nine hundred ninety-four thousand, nine hundred eighty-one".