21520234 has 8 divisors (see below), whose sum is σ = 32516388. Its totient is φ = 10681440.

The previous prime is 21520229. The next prime is 21520241. The reversal of 21520234 is 43202512.

It can be written as a sum of positive squares in 2 ways, for example, as 20277009 + 1243225 = 4503^2 + 1115^2 .

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38997 + ... + 39544.

Almost surely, 2^21520234 is an apocalyptic number.

21520234 is a deficient number, since it is larger than the sum of its proper divisors (10996154).

21520234 is a wasteful number, since it uses less digits than its factorization.

21520234 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78680.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 21520234 is about 4638.9906229696. The cubic root of 21520234 is about 278.1520914400.

Adding to 21520234 its reverse (43202512), we get a palindrome (64722746).

It can be divided in two parts, 215 and 20234, that added together give a square (20449 = 143²).

The spelling of 21520234 in words is "twenty-one million, five hundred twenty thousand, two hundred thirty-four".