91990651 has 2 divisors, whose sum is σ = 91990652. Its totient is φ = 91990650.

The previous prime is 91990649. The next prime is 91990673. The reversal of 91990651 is 15609919.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91990651 - 2¹ = 91990649 is a prime.

Together with 91990649, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (91990601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45995325 + 45995326.

It is an arithmetic number, because the mean of its divisors is an integer number (45995326).

Almost surely, 2^91990651 is an apocalyptic number.

91990651 is a deficient number, since it is larger than the sum of its proper divisors (1).

91990651 is an equidigital number, since it uses as much as digits as its factorization.

91990651 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21870, while the sum is 40.

The square root of 91990651 is about 9591.1756839295. The cubic root of 91990651 is about 451.4204514614.

The spelling of 91990651 in words is "ninety-one million, nine hundred ninety thousand, six hundred fifty-one".