81049691 has 2 divisors, whose sum is σ = 81049692. Its totient is φ = 81049690.

The previous prime is 81049681. The next prime is 81049729. The reversal of 81049691 is 19694018.

It is a happy number.

It is an a-pointer prime, because the next prime (81049729) can be obtained adding 81049691 to its sum of digits (38).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81049691 - 2¹⁴ = 81033307 is a prime.

It is a super-2 number, since 2×81049691² = 13138104822390962, 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 (81049621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40524845 + 40524846.

It is an arithmetic number, because the mean of its divisors is an integer number (40524846).

Almost surely, 2^81049691 is an apocalyptic number.

81049691 is a deficient number, since it is larger than the sum of its proper divisors (1).

81049691 is an equidigital number, since it uses as much as digits as its factorization.

81049691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 81049691 is about 9002.7601878535. The cubic root of 81049691 is about 432.7633305654.

The spelling of 81049691 in words is "eighty-one million, forty-nine thousand, six hundred ninety-one".