917749421 has 2 divisors, whose sum is σ = 917749422. Its totient is φ = 917749420.

The previous prime is 917749409. The next prime is 917749447. The reversal of 917749421 is 124947719.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 554084521 + 363664900 = 23539^2 + 19070^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-917749421 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (917746421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 458874710 + 458874711.

It is an arithmetic number, because the mean of its divisors is an integer number (458874711).

Almost surely, 2^917749421 is an apocalyptic number.

It is an amenable number.

917749421 is a deficient number, since it is larger than the sum of its proper divisors (1).

917749421 is an equidigital number, since it uses as much as digits as its factorization.

917749421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 44.

The square root of 917749421 is about 30294.3793631756. The cubic root of 917749421 is about 971.7951032854.

The spelling of 917749421 in words is "nine hundred seventeen million, seven hundred forty-nine thousand, four hundred twenty-one".