21740928 has 64 divisors (see below), whose sum is σ = 63011520. Its totient is φ = 6586880.

The previous prime is 21740903. The next prime is 21740963. The reversal of 21740928 is 82904712.

It is a happy number.

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

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

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, 1651 + ... + 6797.

It is an arithmetic number, because the mean of its divisors is an integer number (984555).

Almost surely, 2^21740928 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 21740928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31505760).

21740928 is an abundant number, since it is smaller than the sum of its proper divisors (41270592).

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

21740928 is a wasteful number, since it uses less digits than its factorization.

21740928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5175 (or 5163 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 21740928 is about 4662.7168046108. The cubic root of 21740928 is about 279.0996933076.

The spelling of 21740928 in words is "twenty-one million, seven hundred forty thousand, nine hundred twenty-eight".