21163994 has 8 divisors (see below), whose sum is σ = 31911060. Its totient is φ = 10526976.

The previous prime is 21163993. The next prime is 21163999. The reversal of 21163994 is 49936112.

It can be written as a sum of positive squares in 2 ways, for example, as 19245769 + 1918225 = 4387^2 + 1385^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21163991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27029 + ... + 27800.

Almost surely, 2^21163994 is an apocalyptic number.

21163994 is a deficient number, since it is larger than the sum of its proper divisors (10747066).

21163994 is a wasteful number, since it uses less digits than its factorization.

21163994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55024.

The product of its digits is 11664, while the sum is 35.

The square root of 21163994 is about 4600.4341099509. The cubic root of 21163994 is about 276.6087261129.

The spelling of 21163994 in words is "twenty-one million, one hundred sixty-three thousand, nine hundred ninety-four".