421237991 has 2 divisors, whose sum is σ = 421237992. Its totient is φ = 421237990.

The previous prime is 421237987. The next prime is 421238047. The reversal of 421237991 is 199732124.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 421237991 - 2² = 421237987 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421237931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210618995 + 210618996.

It is an arithmetic number, because the mean of its divisors is an integer number (210618996).

Almost surely, 2^421237991 is an apocalyptic number.

421237991 is a deficient number, since it is larger than the sum of its proper divisors (1).

421237991 is an equidigital number, since it uses as much as digits as its factorization.

421237991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 38.

The square root of 421237991 is about 20524.0831951150. The cubic root of 421237991 is about 749.6223230306.

The spelling of 421237991 in words is "four hundred twenty-one million, two hundred thirty-seven thousand, nine hundred ninety-one".