21749544 has 48 divisors (see below), whose sum is σ = 59123220. Its totient is φ = 7223040.

The previous prime is 21749531. The next prime is 21749549. The reversal of 21749544 is 44594712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19027044 + 2722500 = 4362^2 + 1650^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21749499 and 21749508.

It is not an unprimeable number, because it can be changed into a prime (21749549) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32574 + ... + 33234.

Almost surely, 2^21749544 is an apocalyptic number.

21749544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21749544 is an abundant number, since it is smaller than the sum of its proper divisors (37373676).

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

21749544 is a wasteful number, since it uses less digits than its factorization.

21749544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1130 (or 1123 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21749544 is about 4663.6406379566. The cubic root of 21749544 is about 279.1365578082.

The spelling of 21749544 in words is "twenty-one million, seven hundred forty-nine thousand, five hundred forty-four".