21821994 has 32 divisors (see below), whose sum is σ = 51048000. Its totient is φ = 6890832.

The previous prime is 21821981. The next prime is 21822001. The reversal of 21821994 is 49912812.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9609 + ... + 11660.

It is an arithmetic number, because the mean of its divisors is an integer number (1595250).

Almost surely, 2^21821994 is an apocalyptic number.

21821994 is an abundant number, since it is smaller than the sum of its proper divisors (29226006).

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

21821994 is a wasteful number, since it uses less digits than its factorization.

21821994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21299 (or 21293 counting only the distinct ones).

The product of its digits is 10368, while the sum is 36.

The square root of 21821994 is about 4671.4017168298. The cubic root of 21821994 is about 279.4461586227.

The spelling of 21821994 in words is "twenty-one million, eight hundred twenty-one thousand, nine hundred ninety-four".