420331991 has 2 divisors, whose sum is σ = 420331992. Its totient is φ = 420331990.

The previous prime is 420331973. The next prime is 420332023. The reversal of 420331991 is 199133024.

It is an a-pointer prime, because the next prime (420332023) can be obtained adding 420331991 to its sum of digits (32).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 420331991 - 2¹⁴ = 420315607 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (420331921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210165995 + 210165996.

It is an arithmetic number, because the mean of its divisors is an integer number (210165996).

Almost surely, 2^420331991 is an apocalyptic number.

420331991 is a deficient number, since it is larger than the sum of its proper divisors (1).

420331991 is an equidigital number, since it uses as much as digits as its factorization.

420331991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 420331991 is about 20501.9996829578. Note that the first 3 decimals coincide. The cubic root of 420331991 is about 749.0845072484.

The spelling of 420331991 in words is "four hundred twenty million, three hundred thirty-one thousand, nine hundred ninety-one".