21523734 has 48 divisors (see below), whose sum is σ = 50993280. Its totient is φ = 6531840.

The previous prime is 21523727. The next prime is 21523739. The reversal of 21523734 is 43732512.

It is a super-2 number, since 2×21523734² = 926542250605512, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21523698 and 21523707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8352 + ... + 10620.

It is an arithmetic number, because the mean of its divisors is an integer number (1062360).

Almost surely, 2^21523734 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21523734, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25496640).

21523734 is an abundant number, since it is smaller than the sum of its proper divisors (29469546).

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

21523734 is a wasteful number, since it uses less digits than its factorization.

21523734 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2325 (or 2322 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 21523734 is about 4639.3678448685. The cubic root of 21523734 is about 278.1671699556.

It can be divided in two parts, 2152 and 3734, that added together give a triangular number (5886 = T₁₀₈).

The spelling of 21523734 in words is "twenty-one million, five hundred twenty-three thousand, seven hundred thirty-four".