81646253 has 4 divisors (see below), whose sum is σ = 87926748. Its totient is φ = 75365760.

The previous prime is 81646247. The next prime is 81646259. The reversal of 81646253 is 35264618.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (81646247) and next prime (81646259).

It can be written as a sum of positive squares in 2 ways, for example, as 27741289 + 53904964 = 5267^2 + 7342^2 .

It is a cyclic number.

It is not a de Polignac number, because 81646253 - 2⁸ = 81645997 is a prime.

It is a super-2 number, since 2×81646253² = 13332221257880018, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81646259) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3140228 + ... + 3140253.

It is an arithmetic number, because the mean of its divisors is an integer number (21981687).

Almost surely, 2^81646253 is an apocalyptic number.

It is an amenable number.

81646253 is a deficient number, since it is larger than the sum of its proper divisors (6280495).

81646253 is a wasteful number, since it uses less digits than its factorization.

81646253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6280494.

The product of its digits is 34560, while the sum is 35.

The square root of 81646253 is about 9035.8316164037. The cubic root of 81646253 is about 433.8225133800.

The spelling of 81646253 in words is "eighty-one million, six hundred forty-six thousand, two hundred fifty-three".