21193985 has 8 divisors (see below), whose sum is σ = 26928936. Its totient is φ = 15957760.

The previous prime is 21193973. The next prime is 21193993. The reversal of 21193985 is 58939112.

It can be written as a sum of positive squares in 4 ways, for example, as 5764801 + 15429184 = 2401^2 + 3928^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21193985 - 2¹⁶ = 21128449 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124586 + ... + 124755.

It is an arithmetic number, because the mean of its divisors is an integer number (3366117).

Almost surely, 2^21193985 is an apocalyptic number.

It is an amenable number.

21193985 is a deficient number, since it is larger than the sum of its proper divisors (5734951).

21193985 is a wasteful number, since it uses less digits than its factorization.

21193985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249363.

The product of its digits is 19440, while the sum is 38.

The square root of 21193985 is about 4603.6925396903. The cubic root of 21193985 is about 276.7393230252.

The spelling of 21193985 in words is "twenty-one million, one hundred ninety-three thousand, nine hundred eighty-five".