21263504 has 10 divisors (see below), whose sum is σ = 41198070. Its totient is φ = 10631744.

The previous prime is 21263503. The next prime is 21263507. The reversal of 21263504 is 40536212.

It can be written as a sum of positive squares in only one way, i.e., 13690000 + 7573504 = 3700^2 + 2752^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21263504.

It is not an unprimeable number, because it can be changed into a prime (21263503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 664469 + ... + 664500.

It is an arithmetic number, because the mean of its divisors is an integer number (4119807).

Almost surely, 2^21263504 is an apocalyptic number.

It is an amenable number.

21263504 is a deficient number, since it is larger than the sum of its proper divisors (19934566).

21263504 is a wasteful number, since it uses less digits than its factorization.

21263504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1328977 (or 1328971 counting only the distinct ones).

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

The square root of 21263504 is about 4611.2367104715. The cubic root of 21263504 is about 277.0415729980.

Adding to 21263504 its reverse (40536212), we get a palindrome (61799716).

The spelling of 21263504 in words is "twenty-one million, two hundred sixty-three thousand, five hundred four".