21601906 has 8 divisors (see below), whose sum is σ = 32952240. Its totient is φ = 10617828.

The previous prime is 21601903. The next prime is 21601913. The reversal of 21601906 is 60910612.

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 (21601903) by changing a digit.

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, 91416 + ... + 91651.

It is an arithmetic number, because the mean of its divisors is an integer number (4119030).

Almost surely, 2^21601906 is an apocalyptic number.

21601906 is a deficient number, since it is larger than the sum of its proper divisors (11350334).

21601906 is a wasteful number, since it uses less digits than its factorization.

21601906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183128.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 21601906 is about 4647.7850638772. The cubic root of 21601906 is about 278.5035213206.

The spelling of 21601906 in words is "twenty-one million, six hundred one thousand, nine hundred six".