21239936 has 64 divisors (see below), whose sum is σ = 46046880. Its totient is φ = 9719808.

The previous prime is 21239923. The next prime is 21239957. The reversal of 21239936 is 63993212.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-4 number, since 4×21239936⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 21239896 and 21239905.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 93455 + ... + 93681.

Almost surely, 2^21239936 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21239936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23023440).

21239936 is an abundant number, since it is smaller than the sum of its proper divisors (24806944).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21239936 is a wasteful number, since it uses less digits than its factorization.

21239936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301 (or 289 counting only the distinct ones).

The product of its digits is 17496, while the sum is 35.

The square root of 21239936 is about 4608.6805053073. The cubic root of 21239936 is about 276.9391795638.

The spelling of 21239936 in words is "twenty-one million, two hundred thirty-nine thousand, nine hundred thirty-six".