21631406 has 8 divisors (see below), whose sum is σ = 32997240. Its totient is φ = 10632328.

The previous prime is 21631391. The next prime is 21631409. The reversal of 21631406 is 60413612.

It is a happy number.

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 (21631409) 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, 91541 + ... + 91776.

It is an arithmetic number, because the mean of its divisors is an integer number (4124655).

Almost surely, 2^21631406 is an apocalyptic number.

21631406 is a deficient number, since it is larger than the sum of its proper divisors (11365834).

21631406 is a wasteful number, since it uses less digits than its factorization.

21631406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183378.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21631406 is about 4650.9575358199. The cubic root of 21631406 is about 278.6302403364.

The spelling of 21631406 in words is "twenty-one million, six hundred thirty-one thousand, four hundred six".