21001011012 has 36 divisors (see below), whose sum is σ = 53093280240. Its totient is φ = 6999362352.

The previous prime is 21001010983. The next prime is 21001011043. The reversal of 21001011012 is 21011010012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21001011012² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21001010985 and 21001011003.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 250039 + ... + 323297.

It is an arithmetic number, because the mean of its divisors is an integer number (1474813340).

Almost surely, 2^21001011012 is an apocalyptic number.

It is an amenable number.

21001011012 is an abundant number, since it is smaller than the sum of its proper divisors (32092269228).

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

21001011012 is a wasteful number, since it uses less digits than its factorization.

21001011012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81232 (or 81227 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21001011012 its reverse (21011010012), we get a palindrome (42012021024).

The spelling of 21001011012 in words is "twenty-one billion, one million, eleven thousand, twelve".