21011012001 has 12 divisors (see below), whose sum is σ = 34684845312. Its totient is φ = 12006292536.

The previous prime is 21011011997. The next prime is 21011012027. The reversal of 21011012001 is 10021011012.

It is a happy number.

It is not a de Polignac number, because 21011012001 - 2² = 21011011997 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (21011092001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166754001 + ... + 166754126.

It is an arithmetic number, because the mean of its divisors is an integer number (2890403776).

Almost surely, 2^21011012001 is an apocalyptic number.

21011012001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21011012001 is a deficient number, since it is larger than the sum of its proper divisors (13673833311).

21011012001 is a wasteful number, since it uses less digits than its factorization.

21011012001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333508140 (or 333508137 counting only the distinct ones).

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

Adding to 21011012001 its reverse (10021011012), we get a palindrome (31032023013).

It can be divided in two parts, 210110 and 12001, that added together give a triangular number (222111 = T₆₆₆).

The spelling of 21011012001 in words is "twenty-one billion, eleven million, twelve thousand, one".