21306474 has 120 divisors (see below), whose sum is σ = 58989060. Its totient is φ = 5531904.

The previous prime is 21306473. The next prime is 21306479. The reversal of 21306474 is 47460312.

21306474 is a `hidden beast` number, since 2 + 13 + 0 + 647 + 4 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 20766249 + 540225 = 4557^2 + 735^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21306473) 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 59 ways as a sum of consecutive naturals, for example, 734692 + ... + 734720.

Almost surely, 2^21306474 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21306474, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29494530).

21306474 is an abundant number, since it is smaller than the sum of its proper divisors (37682586).

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

21306474 is a wasteful number, since it uses less digits than its factorization.

21306474 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 21306474 is about 4615.8936296236. The cubic root of 21306474 is about 277.2280657228.

Adding to 21306474 its reverse (47460312), we get a palindrome (68766786).

The spelling of 21306474 in words is "twenty-one million, three hundred six thousand, four hundred seventy-four".