21673939 has 4 divisors (see below), whose sum is σ = 24770224. Its totient is φ = 18577656.

The previous prime is 21673921. The next prime is 21673961. The reversal of 21673939 is 93937612.

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

It is a cyclic number.

It is not a de Polignac number, because 21673939 - 2¹¹ = 21671891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21673969) 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, 1548132 + ... + 1548145.

It is an arithmetic number, because the mean of its divisors is an integer number (6192556).

Almost surely, 2^21673939 is an apocalyptic number.

21673939 is a deficient number, since it is larger than the sum of its proper divisors (3096285).

21673939 is an equidigital number, since it uses as much as digits as its factorization.

21673939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3096284.

The product of its digits is 61236, while the sum is 40.

The square root of 21673939 is about 4655.5277896282. The cubic root of 21673939 is about 278.8127407420.

The spelling of 21673939 in words is "twenty-one million, six hundred seventy-three thousand, nine hundred thirty-nine".