21013434 has 48 divisors (see below), whose sum is σ = 49631400. Its totient is φ = 6386688.

The previous prime is 21013427. The next prime is 21013451. The reversal of 21013434 is 43431012.

It can be written as a sum of positive squares in 4 ways, for example, as 9090225 + 11923209 = 3015^2 + 3453^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon 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 23 ways as a sum of consecutive naturals, for example, 20322 + ... + 21330.

Almost surely, 2^21013434 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21013434, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24815700).

21013434 is an abundant number, since it is smaller than the sum of its proper divisors (28617966).

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

21013434 is a wasteful number, since it uses less digits than its factorization.

21013434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1119 (or 1116 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21013434 is about 4584.0412301811. The cubic root of 21013434 is about 275.9512358712.

Adding to 21013434 its reverse (43431012), we get a palindrome (64444446).

The spelling of 21013434 in words is "twenty-one million, thirteen thousand, four hundred thirty-four".