1209997800001 has 27 divisors (see below), whose sum is σ = 1271222506281. Its totient is φ = 1151672553024.

The previous prime is 1209997799999. The next prime is 1209997800013. The reversal of 1209997800001 is 1000087999021.

It is a happy number.

The square root of 1209997800001 is 1099999.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 213346991025 + 996650808976 = 461895^2 + 998324^2 .

It is not a de Polignac number, because 1209997800001 - 2¹ = 1209997799999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1209997800031) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2647697365 + ... + 2647697821.

Almost surely, 2^{1209997800001} is an apocalyptic number.

1209997800001 is the 1099999-th square number.

1209997800001 is the 550000-th centered octagonal number.

It is an amenable number.

1209997800001 is a deficient number, since it is larger than the sum of its proper divisors (61224706280).

1209997800001 is an frugal number, since it uses more digits than its factorization.

1209997800001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1138 (or 569 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 46.

It can be divided in two parts, 12099 and 97800001, that added together give a square (97812100 = 9890²).

The spelling of 1209997800001 in words is "one trillion, two hundred nine billion, nine hundred ninety-seven million, eight hundred thousand, one".