21606955 has 8 divisors (see below), whose sum is σ = 26118432. Its totient is φ = 17158848.

The previous prime is 21606953. The next prime is 21606973. The reversal of 21606955 is 55960612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21606955 - 2¹ = 21606953 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21606955.

It is not an unprimeable number, because it can be changed into a prime (21606953) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15087 + ... + 16456.

It is an arithmetic number, because the mean of its divisors is an integer number (3264804).

Almost surely, 2^21606955 is an apocalyptic number.

21606955 is a deficient number, since it is larger than the sum of its proper divisors (4511477).

21606955 is a wasteful number, since it uses less digits than its factorization.

21606955 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31685.

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 21606955 is about 4648.3281940930. The cubic root of 21606955 is about 278.5252177817.

The spelling of 21606955 in words is "twenty-one million, six hundred six thousand, nine hundred fifty-five".