21519994 has 8 divisors (see below), whose sum is σ = 34178868. Its totient is φ = 10127040.

The previous prime is 21519929. The next prime is 21520003. The reversal of 21519994 is 49991512.

It can be written as a sum of positive squares in 2 ways, for example, as 21501769 + 18225 = 4637^2 + 135^2 .

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

It is a super-2 number, since 2×21519994² = 926220283520072, which contains 22 as substring.

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 3 ways as a sum of consecutive naturals, for example, 316437 + ... + 316504.

Almost surely, 2^21519994 is an apocalyptic number.

21519994 is a deficient number, since it is larger than the sum of its proper divisors (12658874).

21519994 is a wasteful number, since it uses less digits than its factorization.

21519994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 632960.

The product of its digits is 29160, while the sum is 40.

The square root of 21519994 is about 4638.9647552013. The cubic root of 21519994 is about 278.1510574248.

The spelling of 21519994 in words is "twenty-one million, five hundred nineteen thousand, nine hundred ninety-four".