81990107 has 2 divisors, whose sum is σ = 81990108. Its totient is φ = 81990106.

The previous prime is 81990091. The next prime is 81990143. The reversal of 81990107 is 70109918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81990107 - 2⁴ = 81990091 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81990197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40995053 + 40995054.

It is an arithmetic number, because the mean of its divisors is an integer number (40995054).

Almost surely, 2^81990107 is an apocalyptic number.

81990107 is a deficient number, since it is larger than the sum of its proper divisors (1).

81990107 is an equidigital number, since it uses as much as digits as its factorization.

81990107 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 35.

The square root of 81990107 is about 9054.8388721169. The cubic root of 81990107 is about 434.4306763476.

The spelling of 81990107 in words is "eighty-one million, nine hundred ninety thousand, one hundred seven".