21550917 has 8 divisors (see below), whose sum is σ = 30424896. Its totient is φ = 13522112.

The previous prime is 21550901. The next prime is 21550937. The reversal of 21550917 is 71905512.

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 21550917 - 2⁴ = 21550901 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550937) 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, 211233 + ... + 211334.

It is an arithmetic number, because the mean of its divisors is an integer number (3803112).

Almost surely, 2^21550917 is an apocalyptic number.

It is an amenable number.

21550917 is a deficient number, since it is larger than the sum of its proper divisors (8873979).

21550917 is a wasteful number, since it uses less digits than its factorization.

21550917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422587.

The product of its (nonzero) digits is 3150, while the sum is 30.

The square root of 21550917 is about 4642.2965221967. The cubic root of 21550917 is about 278.2842227127.

The spelling of 21550917 in words is "twenty-one million, five hundred fifty thousand, nine hundred seventeen".