21249536 has 120 divisors (see below), whose sum is σ = 54423600. Its totient is φ = 8279040.

The previous prime is 21249523. The next prime is 21249559. The reversal of 21249536 is 63594212.

It is a happy number.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is a Harshad number since it is a multiple of its sum of digits (32).

Its product of digits (12960) is a multiple of the sum of its prime divisors (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1931771 + ... + 1931781.

It is an arithmetic number, because the mean of its divisors is an integer number (453530).

Almost surely, 2^21249536 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 21249536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27211800).

21249536 is an abundant number, since it is smaller than the sum of its proper divisors (33174064).

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

21249536 is an frugal number, since it uses more digits than its factorization.

21249536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61 (or 20 counting only the distinct ones).

The product of its digits is 12960, while the sum is 32.

The square root of 21249536 is about 4609.7219005055. The cubic root of 21249536 is about 276.9808968219.

The spelling of 21249536 in words is "twenty-one million, two hundred forty-nine thousand, five hundred thirty-six".