21052436 has 6 divisors (see below), whose sum is σ = 36841770. Its totient is φ = 10526216.

The previous prime is 21052411. The next prime is 21052469. The reversal of 21052436 is 63425012.

It can be written as a sum of positive squares in only one way, i.e., 20340100 + 712336 = 4510^2 + 844^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2631551 + ... + 2631558.

It is an arithmetic number, because the mean of its divisors is an integer number (6140295).

Almost surely, 2^21052436 is an apocalyptic number.

It is an amenable number.

21052436 is a deficient number, since it is larger than the sum of its proper divisors (15789334).

21052436 is a wasteful number, since it uses less digits than its factorization.

21052436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5263113 (or 5263111 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21052436 is about 4588.2933646401. The cubic root of 21052436 is about 276.1218568540.

Adding to 21052436 its reverse (63425012), we get a palindrome (84477448).

The spelling of 21052436 in words is "twenty-one million, fifty-two thousand, four hundred thirty-six".