78265661 has 2 divisors, whose sum is σ = 78265662. Its totient is φ = 78265660.

The previous prime is 78265609. The next prime is 78265673. The reversal of 78265661 is 16656287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77334436 + 931225 = 8794^2 + 965^2 .

It is a cyclic number.

It is not a de Polignac number, because 78265661 - 2¹⁸ = 78003517 is a prime.

It is a super-2 number, since 2×78265661² = 12251027383533842, 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 (78265261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39132830 + 39132831.

It is an arithmetic number, because the mean of its divisors is an integer number (39132831).

Almost surely, 2^78265661 is an apocalyptic number.

It is an amenable number.

78265661 is a deficient number, since it is larger than the sum of its proper divisors (1).

78265661 is an equidigital number, since it uses as much as digits as its factorization.

78265661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 41.

The square root of 78265661 is about 8846.7881742472. The cubic root of 78265661 is about 427.7503949014.

The spelling of 78265661 in words is "seventy-eight million, two hundred sixty-five thousand, six hundred sixty-one".