21380524 has 48 divisors (see below), whose sum is σ = 43819776. Its totient is φ = 9028800.

The previous prime is 21380521. The next prime is 21380539. The reversal of 21380524 is 42508312.

21380524 = T₁₃₅₂ + T₁₃₅₃ + ... + T₁₃₇₄.

It is not an unprimeable number, because it can be changed into a prime (21380521) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 37159 + ... + 37729.

It is an arithmetic number, because the mean of its divisors is an integer number (912912).

Almost surely, 2^21380524 is an apocalyptic number.

It is an amenable number.

21380524 is an abundant number, since it is smaller than the sum of its proper divisors (22439252).

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

21380524 is a wasteful number, since it uses less digits than its factorization.

21380524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 646 (or 644 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 21380524 is about 4623.9078710545. The cubic root of 21380524 is about 277.5488602654.

Adding to 21380524 its reverse (42508312), we get a palindrome (63888836).

It can be divided in two parts, 21380 and 524, that added together give a square (21904 = 148²).

The spelling of 21380524 in words is "twenty-one million, three hundred eighty thousand, five hundred twenty-four".