21000394 has 8 divisors (see below), whose sum is σ = 31570308. Its totient is φ = 10476960.

The previous prime is 21000391. The next prime is 21000407. The reversal of 21000394 is 49300012.

It can be written as a sum of positive squares in 2 ways, for example, as 20584369 + 416025 = 4537^2 + 645^2 .

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 (21000391) 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, 10467 + ... + 12310.

Almost surely, 2^21000394 is an apocalyptic number.

21000394 is a deficient number, since it is larger than the sum of its proper divisors (10569914).

21000394 is a wasteful number, since it uses less digits than its factorization.

21000394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23240.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 21000394 is about 4582.6186836786. The cubic root of 21000394 is about 275.8941430497.

The spelling of 21000394 in words is "twenty-one million, three hundred ninety-four", and thus it is an aban number.