21493944 has 64 divisors (see below), whose sum is σ = 60192000. Its totient is φ = 7106400.

The previous prime is 21493909. The next prime is 21493951. The reversal of 21493944 is 44939412.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a zygodrome in base 3.

It is a junction number, because it is equal to n+sod(n) for n = 21493899 and 21493908.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32287 + ... + 32945.

It is an arithmetic number, because the mean of its divisors is an integer number (940500).

Almost surely, 2^21493944 is an apocalyptic number.

21493944 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21493944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30096000).

21493944 is an abundant number, since it is smaller than the sum of its proper divisors (38698056).

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

21493944 is a wasteful number, since it uses less digits than its factorization.

21493944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 825 (or 815 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 21493944 is about 4636.1561664810. The cubic root of 21493944 is about 278.0387779524.

The spelling of 21493944 in words is "twenty-one million, four hundred ninety-three thousand, nine hundred forty-four".