21431994 has 8 divisors (see below), whose sum is σ = 42864000. Its totient is φ = 7143996.

The previous prime is 21431983. The next prime is 21432013. The reversal of 21431994 is 49913412.

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

21431994 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1785994 + ... + 1786005.

It is an arithmetic number, because the mean of its divisors is an integer number (5358000).

Almost surely, 2^21431994 is an apocalyptic number.

21431994 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.

21431994 is a wasteful number, since it uses less digits than its factorization.

21431994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3572004.

The product of its digits is 7776, while the sum is 33.

The square root of 21431994 is about 4629.4701640685. The cubic root of 21431994 is about 277.7713991187.

The spelling of 21431994 in words is "twenty-one million, four hundred thirty-one thousand, nine hundred ninety-four".