81570493 has 2 divisors, whose sum is σ = 81570494. Its totient is φ = 81570492.

The previous prime is 81570473. The next prime is 81570563. The reversal of 81570493 is 39407518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79602084 + 1968409 = 8922^2 + 1403^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81570493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81570473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40785246 + 40785247.

It is an arithmetic number, because the mean of its divisors is an integer number (40785247).

Almost surely, 2^81570493 is an apocalyptic number.

It is an amenable number.

81570493 is a deficient number, since it is larger than the sum of its proper divisors (1).

81570493 is an equidigital number, since it uses as much as digits as its factorization.

81570493 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 81570493 is about 9031.6384449335. The cubic root of 81570493 is about 433.6882897699.

The spelling of 81570493 in words is "eighty-one million, five hundred seventy thousand, four hundred ninety-three".