91228639 has 2 divisors, whose sum is σ = 91228640. Its totient is φ = 91228638.

The previous prime is 91228637. The next prime is 91228759. The reversal of 91228639 is 93682219.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91228639 - 2¹ = 91228637 is a prime.

Together with 91228637, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91228637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45614319 + 45614320.

It is an arithmetic number, because the mean of its divisors is an integer number (45614320).

Almost surely, 2^91228639 is an apocalyptic number.

91228639 is a deficient number, since it is larger than the sum of its proper divisors (1).

91228639 is an equidigital number, since it uses as much as digits as its factorization.

91228639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46656, while the sum is 40.

The square root of 91228639 is about 9551.3684359886. The cubic root of 91228639 is about 450.1705345421.

The spelling of 91228639 in words is "ninety-one million, two hundred twenty-eight thousand, six hundred thirty-nine".