21673949 has 4 divisors (see below), whose sum is σ = 23644320. Its totient is φ = 19703580.

The previous prime is 21673921. The next prime is 21673961. The reversal of 21673949 is 94937612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21673949 - 2²⁴ = 4896733 is a prime.

It is a Duffinian number.

It is a congruent 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, 985169 + ... + 985190.

It is an arithmetic number, because the mean of its divisors is an integer number (5911080).

Almost surely, 2^21673949 is an apocalyptic number.

It is an amenable number.

21673949 is a deficient number, since it is larger than the sum of its proper divisors (1970371).

21673949 is a wasteful number, since it uses less digits than its factorization.

21673949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1970370.

The product of its digits is 81648, while the sum is 41.

The square root of 21673949 is about 4655.5288636201. The cubic root of 21673949 is about 278.8127836219.

It can be divided in two parts, 21673 and 949, that added together give a palindrome (22622).

The spelling of 21673949 in words is "twenty-one million, six hundred seventy-three thousand, nine hundred forty-nine".