81493751 has 2 divisors, whose sum is σ = 81493752. Its totient is φ = 81493750.

The previous prime is 81493739. The next prime is 81493777. The reversal of 81493751 is 15739418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81493751 - 2¹⁰ = 81492727 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81493781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40746875 + 40746876.

It is an arithmetic number, because the mean of its divisors is an integer number (40746876).

Almost surely, 2^81493751 is an apocalyptic number.

81493751 is a deficient number, since it is larger than the sum of its proper divisors (1).

81493751 is an equidigital number, since it uses as much as digits as its factorization.

81493751 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 38.

The square root of 81493751 is about 9027.3889358995. The cubic root of 81493751 is about 433.5522415974.

The spelling of 81493751 in words is "eighty-one million, four hundred ninety-three thousand, seven hundred fifty-one".