428509991 has 32 divisors (see below), whose sum is σ = 538312320. Its totient is φ = 332107776.

The previous prime is 428509967. The next prime is 428509999. The reversal of 428509991 is 199905824.

It is not a de Polignac number, because 428509991 - 2¹⁰ = 428508967 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (428509999) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1271375 + ... + 1271711.

It is an arithmetic number, because the mean of its divisors is an integer number (16822260).

Almost surely, 2^428509991 is an apocalyptic number.

428509991 is a deficient number, since it is larger than the sum of its proper divisors (109802329).

428509991 is a wasteful number, since it uses less digits than its factorization.

428509991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 603.

The product of its (nonzero) digits is 233280, while the sum is 47.

The square root of 428509991 is about 20700.4828687642. The cubic root of 428509991 is about 753.9114121965.

It can be divided in two parts, 4285099 and 91, that multiplied together give a square (389944009 = 19747²).

The spelling of 428509991 in words is "four hundred twenty-eight million, five hundred nine thousand, nine hundred ninety-one".