21998427 has 32 divisors (see below), whose sum is σ = 33384960. Its totient is φ = 12768000.

The previous prime is 21998423. The next prime is 21998453. The reversal of 21998427 is 72489912.

It is not a de Polignac number, because 21998427 - 2² = 21998423 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21998423) 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, 95949 + ... + 96177.

It is an arithmetic number, because the mean of its divisors is an integer number (1043280).

Almost surely, 2^21998427 is an apocalyptic number.

21998427 is a deficient number, since it is larger than the sum of its proper divisors (11386533).

21998427 is a wasteful number, since it uses less digits than its factorization.

21998427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355.

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

The square root of 21998427 is about 4690.2480744626. The cubic root of 21998427 is about 280.1972547126.

The spelling of 21998427 in words is "twenty-one million, nine hundred ninety-eight thousand, four hundred twenty-seven".