21634906 has 8 divisors (see below), whose sum is σ = 32576544. Its totient is φ = 10776060.

The previous prime is 21634871. The next prime is 21634909. The reversal of 21634906 is 60943612.

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

It is not an unprimeable number, because it can be changed into a prime (21634909) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 20040 + ... + 21091.

It is an arithmetic number, because the mean of its divisors is an integer number (4072068).

Almost surely, 2^21634906 is an apocalyptic number.

21634906 is a deficient number, since it is larger than the sum of its proper divisors (10941638).

21634906 is a wasteful number, since it uses less digits than its factorization.

21634906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41396.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 21634906 is about 4651.3337872056. Note that the first 3 decimals coincide. The cubic root of 21634906 is about 278.6452671489.

The spelling of 21634906 in words is "twenty-one million, six hundred thirty-four thousand, nine hundred six".