21103973 has 6 divisors (see below), whose sum is σ = 23197062. Its totient is φ = 19185320.

The previous prime is 21103961. The next prime is 21104011. The reversal of 21103973 is 37930112.

It can be written as a sum of positive squares in only one way, i.e., 20638849 + 465124 = 4543^2 + 682^2 .

It is not a de Polignac number, because 21103973 - 2²⁴ = 4326757 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103933) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87086 + ... + 87327.

It is an arithmetic number, because the mean of its divisors is an integer number (3866177).

Almost surely, 2^21103973 is an apocalyptic number.

It is an amenable number.

21103973 is a deficient number, since it is larger than the sum of its proper divisors (2093089).

21103973 is a wasteful number, since it uses less digits than its factorization.

21103973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174435 (or 174424 counting only the distinct ones).

The product of its (nonzero) digits is 1134, while the sum is 26.

The square root of 21103973 is about 4593.9060721787. The cubic root of 21103973 is about 276.3469914605.

It can be divided in two parts, 211039 and 73, that added together give a palindrome (211112).

The spelling of 21103973 in words is "twenty-one million, one hundred three thousand, nine hundred seventy-three".