78259981 has 2 divisors, whose sum is σ = 78259982. Its totient is φ = 78259980.

The previous prime is 78259897. The next prime is 78259991. The reversal of 78259981 is 18995287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68211081 + 10048900 = 8259^2 + 3170^2 .

It is an emirp because it is prime and its reverse (18995287) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78259981 is a prime.

It is a super-2 number, since 2×78259981² = 12249249252240722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78259991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39129990 + 39129991.

It is an arithmetic number, because the mean of its divisors is an integer number (39129991).

Almost surely, 2^78259981 is an apocalyptic number.

It is an amenable number.

78259981 is a deficient number, since it is larger than the sum of its proper divisors (1).

78259981 is an equidigital number, since it uses as much as digits as its factorization.

78259981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 362880, while the sum is 49.

The square root of 78259981 is about 8846.4671479636. The cubic root of 78259981 is about 427.7400468936.

The spelling of 78259981 in words is "seventy-eight million, two hundred fifty-nine thousand, nine hundred eighty-one".