21012011988 has 24 divisors (see below), whose sum is σ = 53485121760. Its totient is φ = 6367276320.

The previous prime is 21012011983. The next prime is 21012011989. The reversal of 21012011988 is 88911021012.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012011981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79590823 + ... + 79591086.

It is an arithmetic number, because the mean of its divisors is an integer number (2228546740).

Almost surely, 2^21012011988 is an apocalyptic number.

It is an amenable number.

21012011988 is an abundant number, since it is smaller than the sum of its proper divisors (32473109772).

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

21012011988 is a wasteful number, since it uses less digits than its factorization.

21012011988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159181927 (or 159181925 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 33.

21012011988 divided by its sum of digits (33) gives a palindrome (636727636).

The spelling of 21012011988 in words is "twenty-one billion, twelve million, eleven thousand, nine hundred eighty-eight".