78215057 has 2 divisors, whose sum is σ = 78215058. Its totient is φ = 78215056.

The previous prime is 78215041. The next prime is 78215083. The reversal of 78215057 is 75051287.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69239041 + 8976016 = 8321^2 + 2996^2 .

It is a cyclic number.

It is not a de Polignac number, because 78215057 - 2⁴ = 78215041 is a prime.

It is a super-2 number, since 2×78215057² = 12235190283026498, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78215087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39107528 + 39107529.

It is an arithmetic number, because the mean of its divisors is an integer number (39107529).

Almost surely, 2^78215057 is an apocalyptic number.

It is an amenable number.

78215057 is a deficient number, since it is larger than the sum of its proper divisors (1).

78215057 is an equidigital number, since it uses as much as digits as its factorization.

78215057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19600, while the sum is 35.

The square root of 78215057 is about 8843.9276907944. The cubic root of 78215057 is about 427.6581852506.

The spelling of 78215057 in words is "seventy-eight million, two hundred fifteen thousand, fifty-seven".