21580021516 has 18 divisors (see below), whose sum is σ = 38135323212. Its totient is φ = 10685232360.

The previous prime is 21580021513. The next prime is 21580021577. The reversal of 21580021516 is 61512008512.

It is not an unprimeable number, because it can be changed into a prime (21580021511) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 211830 + ... + 296701.

Almost surely, 2^21580021516 is an apocalyptic number.

It is an amenable number.

21580021516 is a deficient number, since it is larger than the sum of its proper divisors (16555301696).

21580021516 is a wasteful number, since it uses less digits than its factorization.

21580021516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508741 (or 508636 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 31.

The spelling of 21580021516 in words is "twenty-one billion, five hundred eighty million, twenty-one thousand, five hundred sixteen".