428391921 has 4 divisors (see below), whose sum is σ = 571189232. Its totient is φ = 285594612.

The previous prime is 428391913. The next prime is 428391923. The reversal of 428391921 is 129193824.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 428391921 - 2³ = 428391913 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 428391921.

It is not an unprimeable number, because it can be changed into a prime (428391923) 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, 71398651 + ... + 71398656.

It is an arithmetic number, because the mean of its divisors is an integer number (142797308).

Almost surely, 2^428391921 is an apocalyptic number.

It is an amenable number.

428391921 is a deficient number, since it is larger than the sum of its proper divisors (142797311).

428391921 is a wasteful number, since it uses less digits than its factorization.

428391921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142797310.

The product of its digits is 31104, while the sum is 39.

The square root of 428391921 is about 20697.6308064474. The cubic root of 428391921 is about 753.8421625492.

The spelling of 428391921 in words is "four hundred twenty-eight million, three hundred ninety-one thousand, nine hundred twenty-one".