21001201011 has 36 divisors (see below), whose sum is σ = 37144996200. Its totient is φ = 11369066688.

The previous prime is 21001200991. The next prime is 21001201127. The reversal of 21001201011 is 11010210012.

It is a happy number.

It is not a de Polignac number, because 21001201011 - 2¹⁸ = 21000938867 is a prime.

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 = 21001200984 and 21001201002.

It is not an unprimeable number, because it can be changed into a prime (21001202011) 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 35 ways as a sum of consecutive naturals, for example, 1244826 + ... + 1261583.

It is an arithmetic number, because the mean of its divisors is an integer number (1031805450).

Almost surely, 2^21001201011 is an apocalyptic number.

21001201011 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21001201011 is a deficient number, since it is larger than the sum of its proper divisors (16143795189).

21001201011 is a wasteful number, since it uses less digits than its factorization.

21001201011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2506448 (or 2506438 counting only the distinct ones).

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

Adding to 21001201011 its reverse (11010210012), we get a palindrome (32011411023).

Subtracting from 21001201011 its reverse (11010210012), we obtain a palindrome (9990990999).

The spelling of 21001201011 in words is "twenty-one billion, one million, two hundred one thousand, eleven".