21021994 has 16 divisors (see below), whose sum is σ = 37012608. Its totient is φ = 8765712.

The previous prime is 21021989. The next prime is 21021997. The reversal of 21021994 is 49912012.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21021997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19774 + ... + 20809.

It is an arithmetic number, because the mean of its divisors is an integer number (2313288).

Almost surely, 2^21021994 is an apocalyptic number.

21021994 is a deficient number, since it is larger than the sum of its proper divisors (15990614).

21021994 is a wasteful number, since it uses less digits than its factorization.

21021994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40629.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 21021994 is about 4584.9748090911. The cubic root of 21021994 is about 275.9887011408.

It can be divided in two parts, 2102 and 1994, that added together give a 12-th power (4096 = 2¹²).

The spelling of 21021994 in words is "twenty-one million, twenty-one thousand, nine hundred ninety-four".