428108921 has 8 divisors (see below), whose sum is σ = 439158888. Its totient is φ = 417088000.

The previous prime is 428108911. The next prime is 428108929. The reversal of 428108921 is 129801824.

It can be written as a sum of positive squares in 4 ways, for example, as 68475625 + 359633296 = 8275^2 + 18964^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-428108921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (428108929) by changing a digit.

It is a Zeisel number, with parameters (18, 23).

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24341 + ... + 38061.

It is an arithmetic number, because the mean of its divisors is an integer number (54894861).

Almost surely, 2^428108921 is an apocalyptic number.

428108921 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

428108921 is a deficient number, since it is larger than the sum of its proper divisors (11049967).

428108921 is a wasteful number, since it uses less digits than its factorization.

428108921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14523.

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 428108921 is about 20690.7931457448. The cubic root of 428108921 is about 753.6761274177.

The spelling of 428108921 in words is "four hundred twenty-eight million, one hundred eight thousand, nine hundred twenty-one".