81249997 has 2 divisors, whose sum is σ = 81249998. Its totient is φ = 81249996.

The previous prime is 81249979. The next prime is 81250019. The reversal of 81249997 is 79994218.

Together with previous prime (81249979) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73599241 + 7650756 = 8579^2 + 2766^2 .

It is a cyclic number.

It is not a de Polignac number, because 81249997 - 2¹¹ = 81247949 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81249997.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81249907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40624998 + 40624999.

It is an arithmetic number, because the mean of its divisors is an integer number (40624999).

Almost surely, 2^81249997 is an apocalyptic number.

It is an amenable number.

81249997 is a deficient number, since it is larger than the sum of its proper divisors (1).

81249997 is an equidigital number, since it uses as much as digits as its factorization.

81249997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 49.

The square root of 81249997 is about 9013.8780222499. The cubic root of 81249997 is about 433.1195473397.

The spelling of 81249997 in words is "eighty-one million, two hundred forty-nine thousand, nine hundred ninety-seven".