21760164 has 72 divisors (see below), whose sum is σ = 58135168. Its totient is φ = 7115040.

The previous prime is 21760163. The next prime is 21760169. The reversal of 21760164 is 46106712.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21760163) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 59109 + ... + 59475.

Almost surely, 2^21760164 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 21760164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29067584).

21760164 is an abundant number, since it is smaller than the sum of its proper divisors (36375004).

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

21760164 is a wasteful number, since it uses less digits than its factorization.

21760164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 447 (or 433 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21760164 is about 4664.7790944481. The cubic root of 21760164 is about 279.1819832491.

Adding to 21760164 its reverse (46106712), we get a palindrome (67866876).

The spelling of 21760164 in words is "twenty-one million, seven hundred sixty thousand, one hundred sixty-four".