78512981 has 4 divisors (see below), whose sum is σ = 79994412. Its totient is φ = 77031552.

The previous prime is 78512977. The next prime is 78512989. The reversal of 78512981 is 18921587.

78512981 = 6265² + 6266².

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 39262756 + 39250225 = 6266^2 + 6265^2 .

It is a cyclic number.

It is not a de Polignac number, because 78512981 - 2² = 78512977 is a prime.

It is a super-2 number, since 2×78512981² = 12328576371012722, 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 (78512989) 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, 740636 + ... + 740741.

It is an arithmetic number, because the mean of its divisors is an integer number (19998603).

Almost surely, 2^78512981 is an apocalyptic number.

78512981 is the 6266-th centered square number.

It is an amenable number.

78512981 is a deficient number, since it is larger than the sum of its proper divisors (1481431).

78512981 is a wasteful number, since it uses less digits than its factorization.

78512981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1481430.

The product of its digits is 40320, while the sum is 41.

The square root of 78512981 is about 8860.7551032629. The cubic root of 78512981 is about 428.2004858178.

The spelling of 78512981 in words is "seventy-eight million, five hundred twelve thousand, nine hundred eighty-one".