90917993 has 2 divisors, whose sum is σ = 90917994. Its totient is φ = 90917992.

The previous prime is 90917969. The next prime is 90918013. The reversal of 90917993 is 39971909.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62220544 + 28697449 = 7888^2 + 5357^2 .

It is a cyclic number.

It is not a de Polignac number, because 90917993 - 2¹⁴ = 90901609 is a prime.

It is a super-2 number, since 2×90917993² = 16532162902296098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (90911993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45458996 + 45458997.

It is an arithmetic number, because the mean of its divisors is an integer number (45458997).

Almost surely, 2^90917993 is an apocalyptic number.

It is an amenable number.

90917993 is a deficient number, since it is larger than the sum of its proper divisors (1).

90917993 is an equidigital number, since it uses as much as digits as its factorization.

90917993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 137781, while the sum is 47.

The square root of 90917993 is about 9535.0927106138. The cubic root of 90917993 is about 449.6589893836.

The spelling of 90917993 in words is "ninety million, nine hundred seventeen thousand, nine hundred ninety-three".