78100661 has 2 divisors, whose sum is σ = 78100662. Its totient is φ = 78100660.

The previous prime is 78100657. The next prime is 78100681. The reversal of 78100661 is 16600187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77545636 + 555025 = 8806^2 + 745^2 .

It is an emirp because it is prime and its reverse (16600187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78100661 - 2² = 78100657 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78100651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39050330 + 39050331.

It is an arithmetic number, because the mean of its divisors is an integer number (39050331).

Almost surely, 2^78100661 is an apocalyptic number.

It is an amenable number.

78100661 is a deficient number, since it is larger than the sum of its proper divisors (1).

78100661 is an equidigital number, since it uses as much as digits as its factorization.

78100661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 78100661 is about 8837.4578358259. The cubic root of 78100661 is about 427.4495883467.

The spelling of 78100661 in words is "seventy-eight million, one hundred thousand, six hundred sixty-one".