81523751 has 2 divisors, whose sum is σ = 81523752. Its totient is φ = 81523750.

The previous prime is 81523697. The next prime is 81523759. The reversal of 81523751 is 15732518.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81523751 is a prime.

It is a super-2 number, since 2×81523751² = 13292243954220002, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81523759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40761875 + 40761876.

It is an arithmetic number, because the mean of its divisors is an integer number (40761876).

Almost surely, 2^81523751 is an apocalyptic number.

81523751 is a deficient number, since it is larger than the sum of its proper divisors (1).

81523751 is an equidigital number, since it uses as much as digits as its factorization.

81523751 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8400, while the sum is 32.

The square root of 81523751 is about 9029.0503930369. The cubic root of 81523751 is about 433.6054357437.

The spelling of 81523751 in words is "eighty-one million, five hundred twenty-three thousand, seven hundred fifty-one".