21901606 has 8 divisors (see below), whose sum is σ = 33302664. Its totient is φ = 10800720.

The previous prime is 21901603. The next prime is 21901613. The reversal of 21901606 is 60610912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74860 + ... + 75151.

It is an arithmetic number, because the mean of its divisors is an integer number (4162833).

Almost surely, 2^21901606 is an apocalyptic number.

21901606 is a deficient number, since it is larger than the sum of its proper divisors (11401058).

21901606 is a wasteful number, since it uses less digits than its factorization.

21901606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150086.

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

The square root of 21901606 is about 4679.9151701714. The cubic root of 21901606 is about 279.7855756314.

The spelling of 21901606 in words is "twenty-one million, nine hundred one thousand, six hundred six".