21167993 has 8 divisors (see below), whose sum is σ = 26391360. Its totient is φ = 16494480.

The previous prime is 21167989. The next prime is 21168023. The reversal of 21167993 is 39976112.

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 21167993 - 2² = 21167989 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21167903) 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, 137378 + ... + 137531.

It is an arithmetic number, because the mean of its divisors is an integer number (3298920).

Almost surely, 2^21167993 is an apocalyptic number.

It is an amenable number.

21167993 is a deficient number, since it is larger than the sum of its proper divisors (5223367).

21167993 is a wasteful number, since it uses less digits than its factorization.

21167993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274927.

The product of its digits is 20412, while the sum is 38.

The square root of 21167993 is about 4600.8687223176. The cubic root of 21167993 is about 276.6261470312.

The spelling of 21167993 in words is "twenty-one million, one hundred sixty-seven thousand, nine hundred ninety-three".