21193945 has 8 divisors (see below), whose sum is σ = 25974144. Its totient is φ = 16594224.

The previous prime is 21193943. The next prime is 21193957. The reversal of 21193945 is 54939112.

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 21193945 - 2¹ = 21193943 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 21193945.

It is not an unprimeable number, because it can be changed into a prime (21193943) 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, 44859 + ... + 45328.

It is an arithmetic number, because the mean of its divisors is an integer number (3246768).

Almost surely, 2^21193945 is an apocalyptic number.

It is an amenable number.

21193945 is a deficient number, since it is larger than the sum of its proper divisors (4780199).

21193945 is an equidigital number, since it uses as much as digits as its factorization.

21193945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90239.

The product of its digits is 9720, while the sum is 34.

The square root of 21193945 is about 4603.6881953495. The cubic root of 21193945 is about 276.7391489258.

The spelling of 21193945 in words is "twenty-one million, one hundred ninety-three thousand, nine hundred forty-five".