420840991 has 8 divisors (see below), whose sum is σ = 422547840. Its totient is φ = 419138688.

The previous prime is 420840989. The next prime is 420841019. The reversal of 420840991 is 199048024.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 420840991 - 2¹ = 420840989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 420840991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (420840911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 490635 + ... + 491491.

It is an arithmetic number, because the mean of its divisors is an integer number (52818480).

Almost surely, 2^420840991 is an apocalyptic number.

420840991 is a deficient number, since it is larger than the sum of its proper divisors (1706849).

420840991 is an equidigital number, since it uses as much as digits as its factorization.

420840991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2273.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 420840991 is about 20514.4093505029. The cubic root of 420840991 is about 749.3867526328.

The spelling of 420840991 in words is "four hundred twenty million, eight hundred forty thousand, nine hundred ninety-one".