21516308304 has 40 divisors (see below), whose sum is σ = 56075702592. Its totient is φ = 7108631040.

The previous prime is 21516308189. The next prime is 21516308321. The reversal of 21516308304 is 40380361512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1978012 + ... + 1988859.

Almost surely, 2^21516308304 is an apocalyptic number.

21516308304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21516308304 is an abundant number, since it is smaller than the sum of its proper divisors (34559394288).

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

21516308304 is a wasteful number, since it uses less digits than its factorization.

21516308304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3966995 (or 3966989 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 33.

Adding to 21516308304 its reverse (40380361512), we get a palindrome (61896669816).

The spelling of 21516308304 in words is "twenty-one billion, five hundred sixteen million, three hundred eight thousand, three hundred four".