21994390 has 32 divisors (see below), whose sum is σ = 43752960. Its totient is φ = 7893600.

The previous prime is 21994369. The next prime is 21994393. The reversal of 21994390 is 9349912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21994393) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7425 + ... + 9955.

It is an arithmetic number, because the mean of its divisors is an integer number (1367280).

Almost surely, 2^21994390 is an apocalyptic number.

21994390 is a deficient number, since it is larger than the sum of its proper divisors (21758570).

21994390 is a wasteful number, since it uses less digits than its factorization.

21994390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2628.

The product of its (nonzero) digits is 17496, while the sum is 37.

The square root of 21994390 is about 4689.8176936849. The cubic root of 21994390 is about 280.1801137065.

The spelling of 21994390 in words is "twenty-one million, nine hundred ninety-four thousand, three hundred ninety".