81909151 has 2 divisors, whose sum is σ = 81909152. Its totient is φ = 81909150.

The previous prime is 81909127. The next prime is 81909173. The reversal of 81909151 is 15190918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81909151 - 2¹⁵ = 81876383 is a prime.

It is a super-3 number, since 3×81909151³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81909851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40954575 + 40954576.

It is an arithmetic number, because the mean of its divisors is an integer number (40954576).

Almost surely, 2^81909151 is an apocalyptic number.

81909151 is a deficient number, since it is larger than the sum of its proper divisors (1).

81909151 is an equidigital number, since it uses as much as digits as its factorization.

81909151 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 34.

The square root of 81909151 is about 9050.3674511039. The cubic root of 81909151 is about 434.2876454671.

The spelling of 81909151 in words is "eighty-one million, nine hundred nine thousand, one hundred fifty-one".