21865734 has 64 divisors (see below), whose sum is σ = 53602560. Its totient is φ = 6552000.

The previous prime is 21865721. The next prime is 21865741. The reversal of 21865734 is 43756812.

21865734 is a `hidden beast` number, since 2 + 1 + 86 + 573 + 4 = 666.

It is a super-2 number, since 2×21865734² = 956220646717512, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 77674 + ... + 77954.

It is an arithmetic number, because the mean of its divisors is an integer number (837540).

Almost surely, 2^21865734 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21865734, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26801280).

21865734 is an abundant number, since it is smaller than the sum of its proper divisors (31736826).

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

21865734 is a wasteful number, since it uses less digits than its factorization.

21865734 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434 (or 428 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21865734 is about 4676.0810514789. The cubic root of 21865734 is about 279.6327412892.

The spelling of 21865734 in words is "twenty-one million, eight hundred sixty-five thousand, seven hundred thirty-four".