21380536 has 8 divisors (see below), whose sum is σ = 40088520. Its totient is φ = 10690264.

The previous prime is 21380521. The next prime is 21380539. The reversal of 21380536 is 63508312.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21380539) 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, 1336276 + ... + 1336291.

It is an arithmetic number, because the mean of its divisors is an integer number (5011065).

Almost surely, 2^21380536 is an apocalyptic number.

It is an amenable number.

21380536 is a deficient number, since it is larger than the sum of its proper divisors (18707984).

21380536 is a wasteful number, since it uses less digits than its factorization.

21380536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2672573 (or 2672569 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21380536 is about 4623.9091686581. The cubic root of 21380536 is about 277.5489121909.

Adding to 21380536 its reverse (63508312), we get a palindrome (84888848).

The spelling of 21380536 in words is "twenty-one million, three hundred eighty thousand, five hundred thirty-six".