81045631 has 2 divisors, whose sum is σ = 81045632. Its totient is φ = 81045630.

The previous prime is 81045589. The next prime is 81045661. The reversal of 81045631 is 13654018.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81045631 - 2⁹ = 81045119 is a prime.

It is a super-2 number, since 2×81045631² = 13136788608376322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81045631.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81045661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40522815 + 40522816.

It is an arithmetic number, because the mean of its divisors is an integer number (40522816).

Almost surely, 2^81045631 is an apocalyptic number.

81045631 is a deficient number, since it is larger than the sum of its proper divisors (1).

81045631 is an equidigital number, since it uses as much as digits as its factorization.

81045631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 81045631 is about 9002.5346986279. The cubic root of 81045631 is about 432.7561043463.

Adding to 81045631 its reverse (13654018), we get a palindrome (94699649).

The spelling of 81045631 in words is "eighty-one million, forty-five thousand, six hundred thirty-one".