21573748 has 48 divisors (see below), whose sum is σ = 46497024. Its totient is φ = 8547840.

The previous prime is 21573719. The next prime is 21573751. The reversal of 21573748 is 84737512.

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, 28665 + ... + 29407.

It is an arithmetic number, because the mean of its divisors is an integer number (968688).

Almost surely, 2^21573748 is an apocalyptic number.

21573748 is a gapful number since it is divisible by the number (28) 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 21573748, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23248512).

21573748 is an abundant number, since it is smaller than the sum of its proper divisors (24923276).

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

21573748 is a wasteful number, since it uses less digits than its factorization.

21573748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832 (or 830 counting only the distinct ones).

The product of its digits is 47040, while the sum is 37.

The square root of 21573748 is about 4644.7548912725. The cubic root of 21573748 is about 278.3824592870.

The spelling of 21573748 in words is "twenty-one million, five hundred seventy-three thousand, seven hundred forty-eight".