81038791 has 2 divisors, whose sum is σ = 81038792. Its totient is φ = 81038790.

The previous prime is 81038767. The next prime is 81038809. The reversal of 81038791 is 19783018.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81038791 - 2¹¹ = 81036743 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81038791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81038701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40519395 + 40519396.

It is an arithmetic number, because the mean of its divisors is an integer number (40519396).

Almost surely, 2^81038791 is an apocalyptic number.

81038791 is a deficient number, since it is larger than the sum of its proper divisors (1).

81038791 is an equidigital number, since it uses as much as digits as its factorization.

81038791 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 37.

The square root of 81038791 is about 9002.1547976026. The cubic root of 81038791 is about 432.7439295793.

It can be divided in two parts, 810 and 38791, that added together give a square (39601 = 199²).

The spelling of 81038791 in words is "eighty-one million, thirty-eight thousand, seven hundred ninety-one".