21553994 has 32 divisors (see below), whose sum is σ = 42685056. Its totient is φ = 7902720.

The previous prime is 21553969. The next prime is 21553997. The reversal of 21553994 is 49935512.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21553997) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1499 + ... + 6734.

It is an arithmetic number, because the mean of its divisors is an integer number (1333908).

Almost surely, 2^21553994 is an apocalyptic number.

21553994 is a deficient number, since it is larger than the sum of its proper divisors (21131062).

21553994 is a wasteful number, since it uses less digits than its factorization.

21553994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8270.

The product of its digits is 48600, while the sum is 38.

The square root of 21553994 is about 4642.6279196162. The cubic root of 21553994 is about 278.2974663844.

The spelling of 21553994 in words is "twenty-one million, five hundred fifty-three thousand, nine hundred ninety-four".