21759164 has 48 divisors (see below), whose sum is σ = 45588480. Its totient is φ = 8890560.

The previous prime is 21759149. The next prime is 21759169. The reversal of 21759164 is 46195712.

It is a super-2 number, since 2×21759164² = 946922435957792, which contains 22 as substring.

Its product of digits (15120) is a multiple of the sum of its prime factors (378).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21759169) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 103019 + ... + 103229.

It is an arithmetic number, because the mean of its divisors is an integer number (949760).

Almost surely, 2^21759164 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 21759164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22794240).

21759164 is an abundant number, since it is smaller than the sum of its proper divisors (23829316).

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

21759164 is a wasteful number, since it uses less digits than its factorization.

21759164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 378 (or 376 counting only the distinct ones).

The product of its digits is 15120, while the sum is 35.

The square root of 21759164 is about 4664.6719070048. The cubic root of 21759164 is about 279.1777065311.

The spelling of 21759164 in words is "twenty-one million, seven hundred fifty-nine thousand, one hundred sixty-four".