81331403 has 2 divisors, whose sum is σ = 81331404. Its totient is φ = 81331402.

The previous prime is 81331379. The next prime is 81331409. The reversal of 81331403 is 30413318.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81331403 - 2⁶ = 81331339 is a prime.

It is a super-2 number, since 2×81331403² = 13229594227896818, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (81331409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40665701 + 40665702.

It is an arithmetic number, because the mean of its divisors is an integer number (40665702).

Almost surely, 2^81331403 is an apocalyptic number.

81331403 is a deficient number, since it is larger than the sum of its proper divisors (1).

81331403 is an equidigital number, since it uses as much as digits as its factorization.

81331403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 81331403 is about 9018.3924842513. The cubic root of 81331403 is about 433.2641494415.

The spelling of 81331403 in words is "eighty-one million, three hundred thirty-one thousand, four hundred three".