917953921 has 4 divisors (see below), whose sum is σ = 928268100. Its totient is φ = 907639744.

The previous prime is 917953891. The next prime is 917953987. The reversal of 917953921 is 129359719.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129359719 = 1619 ⋅79901.

It can be written as a sum of positive squares in 2 ways, for example, as 74632321 + 843321600 = 8639^2 + 29040^2 .

It is a cyclic number.

It is not a de Polignac number, because 917953921 - 2⁵ = 917953889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (917953991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5156956 + ... + 5157133.

It is an arithmetic number, because the mean of its divisors is an integer number (232067025).

Almost surely, 2^917953921 is an apocalyptic number.

It is an amenable number.

917953921 is a deficient number, since it is larger than the sum of its proper divisors (10314179).

917953921 is a wasteful number, since it uses less digits than its factorization.

917953921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10314178.

The product of its digits is 153090, while the sum is 46.

The square root of 917953921 is about 30297.7543887332. The cubic root of 917953921 is about 971.8672788833.

The spelling of 917953921 in words is "nine hundred seventeen million, nine hundred fifty-three thousand, nine hundred twenty-one".