21431898 has 16 divisors (see below), whose sum is σ = 47626560. Its totient is φ = 7143948.

The previous prime is 21431887. The next prime is 21431909. The reversal of 21431898 is 89813412.

It is an interprime number because it is at equal distance from previous prime (21431887) and next prime (21431909).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 198390 + ... + 198497.

It is an arithmetic number, because the mean of its divisors is an integer number (2976660).

Almost surely, 2^21431898 is an apocalyptic number.

21431898 is an abundant number, since it is smaller than the sum of its proper divisors (26194662).

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

21431898 is a wasteful number, since it uses less digits than its factorization.

21431898 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396898 (or 396892 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 21431898 is about 4629.4597956997. The cubic root of 21431898 is about 277.7709843790.

The spelling of 21431898 in words is "twenty-one million, four hundred thirty-one thousand, eight hundred ninety-eight".