21929439 has 64 divisors (see below), whose sum is σ = 38568960. Its totient is φ = 10782720.

The previous prime is 21929437. The next prime is 21929443. The reversal of 21929439 is 93492912.

21929439 = T₁₉₅ + T₁₉₆ + ... + T₅₁₇.

It is not a de Polignac number, because 21929439 - 2¹ = 21929437 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21929397 and 21929406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21929437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 359469 + ... + 359529.

It is an arithmetic number, because the mean of its divisors is an integer number (602640).

Almost surely, 2^21929439 is an apocalyptic number.

21929439 is a deficient number, since it is larger than the sum of its proper divisors (16639521).

21929439 is a wasteful number, since it uses less digits than its factorization.

21929439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160.

The product of its digits is 34992, while the sum is 39.

The square root of 21929439 is about 4682.8878910348. The cubic root of 21929439 is about 279.9040445009.

The spelling of 21929439 in words is "twenty-one million, nine hundred twenty-nine thousand, four hundred thirty-nine".