21749376 has 128 divisors (see below), whose sum is σ = 66585600. Its totient is φ = 6220800.

The previous prime is 21749353. The next prime is 21749419. The reversal of 21749376 is 67394712.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

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, 80121 + ... + 80391.

It is an arithmetic number, because the mean of its divisors is an integer number (520200).

Almost surely, 2^21749376 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 21749376, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33292800).

21749376 is an abundant number, since it is smaller than the sum of its proper divisors (44836224).

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

21749376 is a wasteful number, since it uses less digits than its factorization.

21749376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 318 (or 306 counting only the distinct ones).

The product of its digits is 63504, while the sum is 39.

The square root of 21749376 is about 4663.6226262424. The cubic root of 21749376 is about 279.1358390949.

The spelling of 21749376 in words is "twenty-one million, seven hundred forty-nine thousand, three hundred seventy-six".