21606755 has 8 divisors (see below), whose sum is σ = 26007072. Its totient is φ = 17232768.

The previous prime is 21606751. The next prime is 21606757. The reversal of 21606755 is 55760612.

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 21606755 - 2² = 21606751 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21606751) 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, 4727 + ... + 8096.

It is an arithmetic number, because the mean of its divisors is an integer number (3250884).

Almost surely, 2^21606755 is an apocalyptic number.

21606755 is a deficient number, since it is larger than the sum of its proper divisors (4400317).

21606755 is a wasteful number, since it uses less digits than its factorization.

21606755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13165.

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 21606755 is about 4648.3066809323. The cubic root of 21606755 is about 278.5243584100.

The spelling of 21606755 in words is "twenty-one million, six hundred six thousand, seven hundred fifty-five".