21726474 has 128 divisors (see below), whose sum is σ = 58834944. Its totient is φ = 5184000.

The previous prime is 21726473. The next prime is 21726491. The reversal of 21726474 is 47462712.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21726473) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 529894 + ... + 529934.

It is an arithmetic number, because the mean of its divisors is an integer number (459648).

Almost surely, 2^21726474 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21726474, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29417472).

21726474 is an abundant number, since it is smaller than the sum of its proper divisors (37108470).

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

21726474 is a wasteful number, since it uses less digits than its factorization.

21726474 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132.

The product of its digits is 18816, while the sum is 33.

The square root of 21726474 is about 4661.1665921741. The cubic root of 21726474 is about 279.0378284032.

21726474 divided by its sum of digits (33) gives a triangular number (658378 = T₁₁₄₇).

It can be divided in two parts, 2172 and 6474, that added together give a triangular number (8646 = T₁₃₁).

The spelling of 21726474 in words is "twenty-one million, seven hundred twenty-six thousand, four hundred seventy-four".