921790321 has 9 divisors (see below), whose sum is σ = 934376481. Its totient is φ = 909372672.

The previous prime is 921790313. The next prime is 921790333. The reversal of 921790321 is 123097129.

It is a happy number.

The square root of 921790321 is 30361.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 434263921 + 487526400 = 20839^2 + 22080^2 .

It is not a de Polignac number, because 921790321 - 2³ = 921790313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (921790421) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2944861 + ... + 2945173.

It is an arithmetic number, because the mean of its divisors is an integer number (103819609).

Almost surely, 2^921790321 is an apocalyptic number.

921790321 is the 30361-st square number.

921790321 is the 15181-st centered octagonal number.

It is an amenable number.

921790321 is a deficient number, since it is larger than the sum of its proper divisors (12586160).

921790321 is an frugal number, since it uses more digits than its factorization.

921790321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 820 (or 410 counting only the distinct ones).

The product of its (nonzero) digits is 6804, while the sum is 34.

The cubic root of 921790321 is about 973.2193037299.

The spelling of 921790321 in words is "nine hundred twenty-one million, seven hundred ninety thousand, three hundred twenty-one".