21433949 has 4 divisors (see below), whose sum is σ = 21562464. Its totient is φ = 21305436.

The previous prime is 21433921. The next prime is 21433961. The reversal of 21433949 is 94933412.

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 21433949 - 2²⁰ = 20385373 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 (21433649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64007 + ... + 64340.

It is an arithmetic number, because the mean of its divisors is an integer number (5390616).

Almost surely, 2^21433949 is an apocalyptic number.

It is an amenable number.

21433949 is a deficient number, since it is larger than the sum of its proper divisors (128515).

21433949 is a wasteful number, since it uses less digits than its factorization.

21433949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128514.

The product of its digits is 23328, while the sum is 35.

The square root of 21433949 is about 4629.6813065264. The cubic root of 21433949 is about 277.7798448498.

The spelling of 21433949 in words is "twenty-one million, four hundred thirty-three thousand, nine hundred forty-nine".