21006394 has 8 divisors (see below), whose sum is σ = 31537440. Its totient is φ = 10493916.

The previous prime is 21006379. The next prime is 21006397. The reversal of 21006394 is 49360012.

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 (21006397) 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, 1344 + ... + 6619.

It is an arithmetic number, because the mean of its divisors is an integer number (3942180).

Almost surely, 2^21006394 is an apocalyptic number.

21006394 is a deficient number, since it is larger than the sum of its proper divisors (10531046).

21006394 is a wasteful number, since it uses less digits than its factorization.

21006394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9284.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21006394 is about 4583.2732844551. The cubic root of 21006394 is about 275.9204156875.

The spelling of 21006394 in words is "twenty-one million, six thousand, three hundred ninety-four".