21534340 has 12 divisors (see below), whose sum is σ = 45222156. Its totient is φ = 8613728.

The previous prime is 21534329. The next prime is 21534349. The reversal of 21534340 is 4343512.

It can be written as a sum of positive squares in 2 ways, for example, as 11075584 + 10458756 = 3328^2 + 3234^2 .

It is not an unprimeable number, because it can be changed into a prime (21534349) 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, 538339 + ... + 538378.

It is an arithmetic number, because the mean of its divisors is an integer number (3768513).

Almost surely, 2^21534340 is an apocalyptic number.

21534340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21534340 is an abundant number, since it is smaller than the sum of its proper divisors (23687816).

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

21534340 is a wasteful number, since it uses less digits than its factorization.

21534340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1076726 (or 1076724 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 21534340 is about 4640.5107477518. The cubic root of 21534340 is about 278.2128521863.

Adding to 21534340 its reverse (4343512), we get a palindrome (25877852).

It can be divided in two parts, 21 and 534340, that added together give a square (534361 = 731²).

The spelling of 21534340 in words is "twenty-one million, five hundred thirty-four thousand, three hundred forty".