21145994 has 8 divisors (see below), whose sum is σ = 33584868. Its totient is φ = 9951040.

The previous prime is 21145991. The next prime is 21146023. The reversal of 21145994 is 49954112.

It can be written as a sum of positive squares in 2 ways, for example, as 18601969 + 2544025 = 4313^2 + 1595^2 .

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 (21145991) 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, 310937 + ... + 311004.

Almost surely, 2^21145994 is an apocalyptic number.

21145994 is a deficient number, since it is larger than the sum of its proper divisors (12438874).

21145994 is a wasteful number, since it uses less digits than its factorization.

21145994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621960.

The product of its digits is 12960, while the sum is 35.

The square root of 21145994 is about 4598.4773566910. The cubic root of 21145994 is about 276.5302851961.

The spelling of 21145994 in words is "twenty-one million, one hundred forty-five thousand, nine hundred ninety-four".