21057524 has 6 divisors (see below), whose sum is σ = 36850674. Its totient is φ = 10528760.

The previous prime is 21057523. The next prime is 21057541. The reversal of 21057524 is 42575012.

It can be written as a sum of positive squares in only one way, i.e., 12460900 + 8596624 = 3530^2 + 2932^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21057493 and 21057502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057521) 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 as a sum of consecutive naturals, namely, 2632187 + ... + 2632194.

It is an arithmetic number, because the mean of its divisors is an integer number (6141779).

Almost surely, 2^21057524 is an apocalyptic number.

It is an amenable number.

21057524 is a deficient number, since it is larger than the sum of its proper divisors (15793150).

21057524 is a wasteful number, since it uses less digits than its factorization.

21057524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5264385 (or 5264383 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 21057524 is about 4588.8477856647. The cubic root of 21057524 is about 276.1440996457.

The spelling of 21057524 in words is "twenty-one million, fifty-seven thousand, five hundred twenty-four".