21661134 has 32 divisors (see below), whose sum is σ = 47710080. Its totient is φ = 6501600.

The previous prime is 21661109. The next prime is 21661141. The reversal of 21661134 is 43116612.

It is a congruent number.

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, 5689 + ... + 8699.

It is an arithmetic number, because the mean of its divisors is an integer number (1490940).

Almost surely, 2^21661134 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21661134, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23855040).

21661134 is an abundant number, since it is smaller than the sum of its proper divisors (26048946).

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

21661134 is a wasteful number, since it uses less digits than its factorization.

21661134 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3136.

The product of its digits is 864, while the sum is 24.

The square root of 21661134 is about 4654.1523395781. The cubic root of 21661134 is about 278.7578222449.

Adding to 21661134 its reverse (43116612), we get a palindrome (64777746).

The spelling of 21661134 in words is "twenty-one million, six hundred sixty-one thousand, one hundred thirty-four".