428561991 has 24 divisors (see below), whose sum is σ = 727258896. Its totient is φ = 239754240.

The previous prime is 428561989. The next prime is 428562007. The reversal of 428561991 is 199165824.

428561991 is a `hidden beast` number, since 4 + 28 + 5 + 619 + 9 + 1 = 666.

It is not a de Polignac number, because 428561991 - 2¹ = 428561989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (428561981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 165210 + ... + 167783.

It is an arithmetic number, because the mean of its divisors is an integer number (30302454).

Almost surely, 2^428561991 is an apocalyptic number.

428561991 is a deficient number, since it is larger than the sum of its proper divisors (298696905).

428561991 is a wasteful number, since it uses less digits than its factorization.

428561991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333023 (or 333020 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 428561991 is about 20701.7388400105. The cubic root of 428561991 is about 753.9419068630.

The spelling of 428561991 in words is "four hundred twenty-eight million, five hundred sixty-one thousand, nine hundred ninety-one".