21017964 has 24 divisors (see below), whose sum is σ = 53500608. Its totient is φ = 6369040.

The previous prime is 21017951. The next prime is 21017981. The reversal of 21017964 is 46971012.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79482 + ... + 79745.

It is an arithmetic number, because the mean of its divisors is an integer number (2229192).

Almost surely, 2^21017964 is an apocalyptic number.

It is an amenable number.

21017964 is an abundant number, since it is smaller than the sum of its proper divisors (32482644).

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

21017964 is a wasteful number, since it uses less digits than its factorization.

21017964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159245 (or 159243 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21017964 is about 4584.5353090581. The cubic root of 21017964 is about 275.9710639692.

Adding to 21017964 its reverse (46971012), we get a palindrome (67988976).

The spelling of 21017964 in words is "twenty-one million, seventeen thousand, nine hundred sixty-four".