421018991 has 4 divisors (see below), whose sum is σ = 445784832. Its totient is φ = 396253152.

The previous prime is 421018981. The next prime is 421019003. The reversal of 421018991 is 199810124.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-421018991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421018951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12382895 + ... + 12382928.

It is an arithmetic number, because the mean of its divisors is an integer number (111446208).

Almost surely, 2^421018991 is an apocalyptic number.

421018991 is a deficient number, since it is larger than the sum of its proper divisors (24765841).

421018991 is a wasteful number, since it uses less digits than its factorization.

421018991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24765840.

The product of its (nonzero) digits is 5184, while the sum is 35.

The square root of 421018991 is about 20518.7473058177. The cubic root of 421018991 is about 749.4923919303.

The spelling of 421018991 in words is "four hundred twenty-one million, eighteen thousand, nine hundred ninety-one".