21639206 has 16 divisors (see below), whose sum is σ = 33123840. Its totient is φ = 10600200.

The previous prime is 21639199. The next prime is 21639227. The reversal of 21639206 is 60293612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23405 + ... + 24311.

It is an arithmetic number, because the mean of its divisors is an integer number (2070240).

Almost surely, 2^21639206 is an apocalyptic number.

21639206 is a deficient number, since it is larger than the sum of its proper divisors (11484634).

21639206 is a wasteful number, since it uses less digits than its factorization.

21639206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1139.

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 21639206 is about 4651.7959972467. The cubic root of 21639206 is about 278.6637264430.

The spelling of 21639206 in words is "twenty-one million, six hundred thirty-nine thousand, two hundred six".