78497981 has 4 divisors (see below), whose sum is σ = 78587964. Its totient is φ = 78408000.

The previous prime is 78497977. The next prime is 78497989. The reversal of 78497981 is 18979487.

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 6400900 + 72097081 = 2530^2 + 8491^2 .

It is a cyclic number.

It is not a de Polignac number, because 78497981 - 2² = 78497977 is a prime.

It is a super-2 number, since 2×78497981² = 12323866042152722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78497989) 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, 43670 + ... + 45431.

It is an arithmetic number, because the mean of its divisors is an integer number (19646991).

Almost surely, 2^78497981 is an apocalyptic number.

It is an amenable number.

78497981 is a deficient number, since it is larger than the sum of its proper divisors (89983).

78497981 is an equidigital number, since it uses as much as digits as its factorization.

78497981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89982.

The product of its digits is 1016064, while the sum is 53.

The square root of 78497981 is about 8859.9086338404. The cubic root of 78497981 is about 428.1732146740.

The spelling of 78497981 in words is "seventy-eight million, four hundred ninety-seven thousand, nine hundred eighty-one".