1221001010000 has 100 divisors (see below), whose sum is σ = 3004628776644. Its totient is φ = 480393600000.

The previous prime is 1221001009979. The next prime is 1221001010003. The reversal of 1221001010000 is 101001221.

It can be written as a sum of positive squares in 10 ways, for example, as 1155315420736 + 65685589264 = 1074856^2 + 256292^2 .

It is a tau number, because it is divible by the number of its divisors (100).

It is a Harshad number since it is a multiple of its sum of digits (8).

It is a self number, because there is not a number n which added to its sum of digits gives 1221001010000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221001010003) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 390821 + ... + 1610820.

Almost surely, 2^{1221001010000} is an apocalyptic number.

1221001010000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221001010000 is an abundant number, since it is smaller than the sum of its proper divisors (1783627766644).

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

1221001010000 is an equidigital number, since it uses as much as digits as its factorization.

1221001010000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2001730 (or 2001709 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 1221001010000 its reverse (101001221), we get a palindrome (1221102011221).

It can be divided in two parts, 12 and 21001010000, that added together give a palindrome (21001010012).

The spelling of 1221001010000 in words is "one trillion, two hundred twenty-one billion, one million, ten thousand".