78299021 has 2 divisors, whose sum is σ = 78299022. Its totient is φ = 78299020.

The previous prime is 78299017. The next prime is 78299027. The reversal of 78299021 is 12099287.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76825225 + 1473796 = 8765^2 + 1214^2 .

It is an emirp because it is prime and its reverse (12099287) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78299021 - 2² = 78299017 is a prime.

It is a super-2 number, since 2×78299021² = 12261473379116882, 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 (78299027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39149510 + 39149511.

It is an arithmetic number, because the mean of its divisors is an integer number (39149511).

Almost surely, 2^78299021 is an apocalyptic number.

It is an amenable number.

78299021 is a deficient number, since it is larger than the sum of its proper divisors (1).

78299021 is an equidigital number, since it uses as much as digits as its factorization.

78299021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 78299021 is about 8848.6734033978. The cubic root of 78299021 is about 427.8111611260.

The spelling of 78299021 in words is "seventy-eight million, two hundred ninety-nine thousand, twenty-one".