21993165 has 48 divisors (see below), whose sum is σ = 41558400. Its totient is φ = 10717056.

The previous prime is 21993161. The next prime is 21993187. The reversal of 21993165 is 56139912.

It is not a de Polignac number, because 21993165 - 2² = 21993161 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21993161) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24352 + ... + 25238.

It is an arithmetic number, because the mean of its divisors is an integer number (865800).

Almost surely, 2^21993165 is an apocalyptic number.

It is an amenable number.

21993165 is a deficient number, since it is larger than the sum of its proper divisors (19565235).

21993165 is a wasteful number, since it uses less digits than its factorization.

21993165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 946 (or 943 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 21993165 is about 4689.6870897748. The cubic root of 21993165 is about 280.1749119708.

The spelling of 21993165 in words is "twenty-one million, nine hundred ninety-three thousand, one hundred sixty-five".