521320401391 has 2 divisors, whose sum is σ = 521320401392. Its totient is φ = 521320401390.

The previous prime is 521320401367. The next prime is 521320401403. The reversal of 521320401391 is 193104023125.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 521320401391 - 2⁷ = 521320401263 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521320401331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260660200695 + 260660200696.

It is an arithmetic number, because the mean of its divisors is an integer number (260660200696).

Almost surely, 2^521320401391 is an apocalyptic number.

521320401391 is a deficient number, since it is larger than the sum of its proper divisors (1).

521320401391 is an equidigital number, since it uses as much as digits as its factorization.

521320401391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 31.

The spelling of 521320401391 in words is "five hundred twenty-one billion, three hundred twenty million, four hundred one thousand, three hundred ninety-one".