21002100121000 has 64 divisors (see below), whose sum is σ = 50839566570000. Its totient is φ = 8111155897600.

The previous prime is 21002100120997. The next prime is 21002100121003. The reversal of 21002100121000 is 12100120012.

It is an interprime number because it is at equal distance from previous prime (21002100120997) and next prime (21002100121003).

It can be written as a sum of positive squares in 8 ways, for example, as 4080214162116 + 16921885958884 = 2019954^2 + 4113622^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (21002100121003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 362076175 + ... + 362134174.

Almost surely, 2^{21002100121000} is an apocalyptic number.

21002100121000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002100121000 is an abundant number, since it is smaller than the sum of its proper divisors (29837466449000).

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

21002100121000 is a wasteful number, since it uses less digits than its factorization.

21002100121000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 724210399 (or 724210385 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21002100121000 its reverse (12100120012), we get a palindrome (21014200241012).

The spelling of 21002100121000 in words is "twenty-one trillion, two billion, one hundred million, one hundred twenty-one thousand".