21427998 has 8 divisors (see below), whose sum is σ = 42856008. Its totient is φ = 7142664.

The previous prime is 21427997. The next prime is 21428003. The reversal of 21427998 is 89972412.

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

21427998 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21427997) 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, 1785661 + ... + 1785672.

It is an arithmetic number, because the mean of its divisors is an integer number (5357001).

Almost surely, 2^21427998 is an apocalyptic number.

21427998 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21427998 is a wasteful number, since it uses less digits than its factorization.

21427998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3571338.

The product of its digits is 72576, while the sum is 42.

The square root of 21427998 is about 4629.0385610837. The cubic root of 21427998 is about 277.7541345328.

The spelling of 21427998 in words is "twenty-one million, four hundred twenty-seven thousand, nine hundred ninety-eight".