21612206 has 16 divisors (see below), whose sum is σ = 40417920. Its totient is φ = 8420280.

The previous prime is 21612191. The next prime is 21612211. The reversal of 21612206 is 60221612.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 70016 + ... + 70323.

It is an arithmetic number, because the mean of its divisors is an integer number (2526120).

Almost surely, 2^21612206 is an apocalyptic number.

21612206 is a deficient number, since it is larger than the sum of its proper divisors (18805714).

21612206 is a wasteful number, since it uses less digits than its factorization.

21612206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140359.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21612206 is about 4648.8929865076. The cubic root of 21612206 is about 278.5477786879.

Adding to 21612206 its reverse (60221612), we get a palindrome (81833818).

The spelling of 21612206 in words is "twenty-one million, six hundred twelve thousand, two hundred six".