81029491 has 2 divisors, whose sum is σ = 81029492. Its totient is φ = 81029490.

The previous prime is 81029477. The next prime is 81029513. The reversal of 81029491 is 19492018.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81029491 is a prime.

It is not a weakly prime, because it can be changed into another prime (81029461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40514745 + 40514746.

It is an arithmetic number, because the mean of its divisors is an integer number (40514746).

Almost surely, 2^81029491 is an apocalyptic number.

81029491 is a deficient number, since it is larger than the sum of its proper divisors (1).

81029491 is an equidigital number, since it uses as much as digits as its factorization.

81029491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 81029491 is about 9001.6382397872. The cubic root of 81029491 is about 432.7273750690.

The spelling of 81029491 in words is "eighty-one million, twenty-nine thousand, four hundred ninety-one".