21631206 has 8 divisors (see below), whose sum is σ = 43262424. Its totient is φ = 7210400.

The previous prime is 21631171. The next prime is 21631213. The reversal of 21631206 is 60213612.

It is a happy number.

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

21631206 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1802595 + ... + 1802606.

It is an arithmetic number, because the mean of its divisors is an integer number (5407803).

Almost surely, 2^21631206 is an apocalyptic number.

21631206 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21631206 is a wasteful number, since it uses less digits than its factorization.

21631206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3605206.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21631206 is about 4650.9360348214. The cubic root of 21631206 is about 278.6293816124.

Adding to 21631206 its reverse (60213612), we get a palindrome (81844818).

The spelling of 21631206 in words is "twenty-one million, six hundred thirty-one thousand, two hundred six".