21013764 has 24 divisors (see below), whose sum is σ = 49361088. Its totient is φ = 6957600.

The previous prime is 21013723. The next prime is 21013781. The reversal of 21013764 is 46731012.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 3987 + ... + 7610.

It is an arithmetic number, because the mean of its divisors is an integer number (2056712).

Almost surely, 2^21013764 is an apocalyptic number.

It is an amenable number.

21013764 is an abundant number, since it is smaller than the sum of its proper divisors (28347324).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21013764 is a wasteful number, since it uses less digits than its factorization.

21013764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11755 (or 11753 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21013764 is about 4584.0772244804. The cubic root of 21013764 is about 275.9526803984.

Adding to 21013764 its reverse (46731012), we get a palindrome (67744776).

The spelling of 21013764 in words is "twenty-one million, thirteen thousand, seven hundred sixty-four".