91820987 has 2 divisors, whose sum is σ = 91820988. Its totient is φ = 91820986.

The previous prime is 91820969. The next prime is 91821001. The reversal of 91820987 is 78902819.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91820987 - 2⁶ = 91820923 is a prime.

It is not a weakly prime, because it can be changed into another prime (91820957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45910493 + 45910494.

It is an arithmetic number, because the mean of its divisors is an integer number (45910494).

Almost surely, 2^91820987 is an apocalyptic number.

91820987 is a deficient number, since it is larger than the sum of its proper divisors (1).

91820987 is an equidigital number, since it uses as much as digits as its factorization.

91820987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 91820987 is about 9582.3268051137. The cubic root of 91820987 is about 451.1427531904.

The spelling of 91820987 in words is "ninety-one million, eight hundred twenty thousand, nine hundred eighty-seven".