21611606 has 4 divisors (see below), whose sum is σ = 32417412. Its totient is φ = 10805802.

The previous prime is 21611591. The next prime is 21611609. The reversal of 21611606 is 60611612.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21611609) 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 as a sum of consecutive naturals, namely, 5402900 + ... + 5402903.

It is an arithmetic number, because the mean of its divisors is an integer number (8104353).

Almost surely, 2^21611606 is an apocalyptic number.

21611606 is a deficient number, since it is larger than the sum of its proper divisors (10805806).

21611606 is a wasteful number, since it uses less digits than its factorization.

21611606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10805805.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21611606 is about 4648.8284545679. The cubic root of 21611606 is about 278.5452009746.

The spelling of 21611606 in words is "twenty-one million, six hundred eleven thousand, six hundred six".