21311504 has 10 divisors (see below), whose sum is σ = 41291070. Its totient is φ = 10655744.

The previous prime is 21311503. The next prime is 21311527. The reversal of 21311504 is 40511312.

It can be written as a sum of positive squares in only one way, i.e., 18939904 + 2371600 = 4352^2 + 1540^2 .

It is not an unprimeable number, because it can be changed into a prime (21311503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 665969 + ... + 666000.

It is an arithmetic number, because the mean of its divisors is an integer number (4129107).

Almost surely, 2^21311504 is an apocalyptic number.

It is an amenable number.

21311504 is a deficient number, since it is larger than the sum of its proper divisors (19979566).

21311504 is a wasteful number, since it uses less digits than its factorization.

21311504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1331977 (or 1331971 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21311504 is about 4616.4384540466. The cubic root of 21311504 is about 277.2498798664.

Adding to 21311504 its reverse (40511312), we get a palindrome (61822816).

The spelling of 21311504 in words is "twenty-one million, three hundred eleven thousand, five hundred four".