21019673 has 4 divisors (see below), whose sum is σ = 21141348. Its totient is φ = 20898000.

The previous prime is 21019657. The next prime is 21019699. The reversal of 21019673 is 37691012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15784729 + 5234944 = 3973^2 + 2288^2 .

It is a cyclic number.

It is not a de Polignac number, because 21019673 - 2⁴ = 21019657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21019613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60578 + ... + 60923.

It is an arithmetic number, because the mean of its divisors is an integer number (5285337).

Almost surely, 2^21019673 is an apocalyptic number.

It is an amenable number.

21019673 is a deficient number, since it is larger than the sum of its proper divisors (121675).

21019673 is a wasteful number, since it uses less digits than its factorization.

21019673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121674.

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 21019673 is about 4584.7216927530. The cubic root of 21019673 is about 275.9785436306.

The spelling of 21019673 in words is "twenty-one million, nineteen thousand, six hundred seventy-three".