21724734 has 8 divisors (see below), whose sum is σ = 43449480. Its totient is φ = 7241576.

The previous prime is 21724721. The next prime is 21724739. The reversal of 21724734 is 43742712.

It is a sphenic number, since it is the product of 3 distinct primes.

21724734 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21724739) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1810389 + ... + 1810400.

It is an arithmetic number, because the mean of its divisors is an integer number (5431185).

Almost surely, 2^21724734 is an apocalyptic number.

21724734 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21724734 is a wasteful number, since it uses less digits than its factorization.

21724734 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3620794.

The product of its digits is 9408, while the sum is 30.

The square root of 21724734 is about 4660.9799398839. The cubic root of 21724734 is about 279.0303791383.

The spelling of 21724734 in words is "twenty-one million, seven hundred twenty-four thousand, seven hundred thirty-four".