21738132 has 90 divisors (see below), whose sum is σ = 61690398. Its totient is φ = 6671808.

The previous prime is 21738131. The next prime is 21738133. The reversal of 21738132 is 23183712.

It is an interprime number because it is at equal distance from previous prime (21738131) and next prime (21738133).

It can be written as a sum of positive squares in 3 ways, for example, as 171396 + 21566736 = 414^2 + 4644^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21738096 and 21738105.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21738131) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 54558 + ... + 54954.

Almost surely, 2^21738132 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 21738132, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30845199).

21738132 is an abundant number, since it is smaller than the sum of its proper divisors (39952266).

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

21738132 is a wasteful number, since it uses less digits than its factorization.

21738132 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 439 (or 415 counting only the distinct ones).

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

The square root of 21738132 is about 4662.4169697701. The cubic root of 21738132 is about 279.0877282219.

The spelling of 21738132 in words is "twenty-one million, seven hundred thirty-eight thousand, one hundred thirty-two".