420991555 has 4 divisors (see below), whose sum is σ = 505189872. Its totient is φ = 336793240.

The previous prime is 420991541. The next prime is 420991601. The reversal of 420991555 is 555199024.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 420991555 - 2⁵ = 420991523 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42099151 + ... + 42099160.

It is an arithmetic number, because the mean of its divisors is an integer number (126297468).

Almost surely, 2^420991555 is an apocalyptic number.

420991555 is a deficient number, since it is larger than the sum of its proper divisors (84198317).

420991555 is an equidigital number, since it uses as much as digits as its factorization.

420991555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84198316.

The product of its (nonzero) digits is 81000, while the sum is 40.

The square root of 420991555 is about 20518.0787355932. The cubic root of 420991555 is about 749.4761111762.

The spelling of 420991555 in words is "four hundred twenty million, nine hundred ninety-one thousand, five hundred fifty-five".