81508253 has 2 divisors, whose sum is σ = 81508254. Its totient is φ = 81508252.

The previous prime is 81508237. The next prime is 81508279. The reversal of 81508253 is 35280518.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74011609 + 7496644 = 8603^2 + 2738^2 .

It is a cyclic number.

It is not a de Polignac number, because 81508253 - 2⁴ = 81508237 is a prime.

It is a super-2 number, since 2×81508253² = 13287190614224018, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81501253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40754126 + 40754127.

It is an arithmetic number, because the mean of its divisors is an integer number (40754127).

Almost surely, 2^81508253 is an apocalyptic number.

It is an amenable number.

81508253 is a deficient number, since it is larger than the sum of its proper divisors (1).

81508253 is an equidigital number, since it uses as much as digits as its factorization.

81508253 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9600, while the sum is 32.

The square root of 81508253 is about 9028.1921224573. The cubic root of 81508253 is about 433.5779572775.

The spelling of 81508253 in words is "eighty-one million, five hundred eight thousand, two hundred fifty-three".