21012120201009 has 128 divisors (see below), whose sum is σ = 34618115952640. Its totient is φ = 11068427575296.

The previous prime is 21012120201001. The next prime is 21012120201011. The reversal of 21012120201009 is 90010202121012.

It is not a de Polignac number, because 21012120201009 - 2³ = 21012120201001 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21012120201001) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 11218429497 + ... + 11218431369.

It is an arithmetic number, because the mean of its divisors is an integer number (270454030880).

Almost surely, 2^{21012120201009} is an apocalyptic number.

It is an amenable number.

21012120201009 is a deficient number, since it is larger than the sum of its proper divisors (13605995751631).

21012120201009 is a wasteful number, since it uses less digits than its factorization.

21012120201009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4071.

The product of its (nonzero) digits is 144, while the sum is 21.

It can be divided in two parts, 21012 and 120201009, that added together give a palindrome (120222021).

The spelling of 21012120201009 in words is "twenty-one trillion, twelve billion, one hundred twenty million, two hundred one thousand, nine".