81157207 has 2 divisors, whose sum is σ = 81157208. Its totient is φ = 81157206.

The previous prime is 81157177. The next prime is 81157217. The reversal of 81157207 is 70275118.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81157207 - 2¹⁹ = 80632919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81157217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40578603 + 40578604.

It is an arithmetic number, because the mean of its divisors is an integer number (40578604).

Almost surely, 2^81157207 is an apocalyptic number.

81157207 is a deficient number, since it is larger than the sum of its proper divisors (1).

81157207 is an equidigital number, since it uses as much as digits as its factorization.

81157207 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 81157207 is about 9008.7294886682. The cubic root of 81157207 is about 432.9546059117.

The spelling of 81157207 in words is "eighty-one million, one hundred fifty-seven thousand, two hundred seven".