320621531 has 2 divisors, whose sum is σ = 320621532. Its totient is φ = 320621530.

The previous prime is 320621519. The next prime is 320621537. The reversal of 320621531 is 135126023.

It is a strong prime.

It is an emirp because it is prime and its reverse (135126023) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 320621531 - 2⁶ = 320621467 is a prime.

It is a super-2 number, since 2×320621531² = 205596332281567922, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 320621497 and 320621506.

It is not a weakly prime, because it can be changed into another prime (320621537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160310765 + 160310766.

It is an arithmetic number, because the mean of its divisors is an integer number (160310766).

Almost surely, 2^320621531 is an apocalyptic number.

320621531 is a deficient number, since it is larger than the sum of its proper divisors (1).

320621531 is an equidigital number, since it uses as much as digits as its factorization.

320621531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 23.

The square root of 320621531 is about 17905.9077122608. The cubic root of 320621531 is about 684.4329268844.

Adding to 320621531 its reverse (135126023), we get a palindrome (455747554).

The spelling of 320621531 in words is "three hundred twenty million, six hundred twenty-one thousand, five hundred thirty-one".