21005011716 has 24 divisors (see below), whose sum is σ = 52781824704. Its totient is φ = 6463080480.

The previous prime is 21005011693. The next prime is 21005011771. The reversal of 21005011716 is 61711050012.

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, 67323600 + ... + 67323911.

It is an arithmetic number, because the mean of its divisors is an integer number (2199242696).

Almost surely, 2^21005011716 is an apocalyptic number.

21005011716 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21005011716 is an abundant number, since it is smaller than the sum of its proper divisors (31776812988).

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

21005011716 is a wasteful number, since it uses less digits than its factorization.

21005011716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134647531 (or 134647529 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 24.

Adding to 21005011716 its reverse (61711050012), we get a palindrome (82716061728).

The spelling of 21005011716 in words is "twenty-one billion, five million, eleven thousand, seven hundred sixteen".