21550906 has 8 divisors (see below), whose sum is σ = 34813044. Its totient is φ = 9946560.

The previous prime is 21550901. The next prime is 21550937. The reversal of 21550906 is 60905512.

It can be written as a sum of positive squares in 2 ways, for example, as 21242881 + 308025 = 4609^2 + 555^2 .

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 (21550901) 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, 414415 + ... + 414466.

Almost surely, 2^21550906 is an apocalyptic number.

21550906 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21550906 is a deficient number, since it is larger than the sum of its proper divisors (13262138).

21550906 is a wasteful number, since it uses less digits than its factorization.

21550906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 828896.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 21550906 is about 4642.2953374382. The cubic root of 21550906 is about 278.2841753655.

The spelling of 21550906 in words is "twenty-one million, five hundred fifty thousand, nine hundred six".