21011211988 has 24 divisors (see below), whose sum is σ = 41319710208. Its totient is φ = 9275852256.

The previous prime is 21011211929. The next prime is 21011212031. The reversal of 21011211988 is 88911211012.

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, 8782756 + ... + 8785147.

It is an arithmetic number, because the mean of its divisors is an integer number (1721654592).

Almost surely, 2^21011211988 is an apocalyptic number.

It is an amenable number.

21011211988 is a deficient number, since it is larger than the sum of its proper divisors (20308498220).

21011211988 is a wasteful number, since it uses less digits than its factorization.

21011211988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17567943 (or 17567941 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 34.

The spelling of 21011211988 in words is "twenty-one billion, eleven million, two hundred eleven thousand, nine hundred eighty-eight".