90991213 has 2 divisors, whose sum is σ = 90991214. Its totient is φ = 90991212.

The previous prime is 90991193. The next prime is 90991217. The reversal of 90991213 is 31219909.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55980324 + 35010889 = 7482^2 + 5917^2 .

It is a cyclic number.

It is not a de Polignac number, because 90991213 - 2⁵ = 90991181 is a prime.

It is a super-2 number, since 2×90991213² = 16558801686422738, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90991217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45495606 + 45495607.

It is an arithmetic number, because the mean of its divisors is an integer number (45495607).

Almost surely, 2^90991213 is an apocalyptic number.

It is an amenable number.

90991213 is a deficient number, since it is larger than the sum of its proper divisors (1).

90991213 is an equidigital number, since it uses as much as digits as its factorization.

90991213 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 90991213 is about 9538.9314391078. The cubic root of 90991213 is about 449.7796666214.

It can be divided in two parts, 90991 and 213, that added together give a square (91204 = 302²).

The spelling of 90991213 in words is "ninety million, nine hundred ninety-one thousand, two hundred thirteen".