1781199109901 has 4 divisors (see below), whose sum is σ = 1782943674204. Its totient is φ = 1779454545600.

The previous prime is 1781199109891. The next prime is 1781199109913. The reversal of 1781199109901 is 1099019911871.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1388565283876 + 392633826025 = 1178374^2 + 626605^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1781199109901 is a prime.

It is a super-2 number, since 2×1781199109901² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1781199102901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 872280620 + ... + 872282661.

It is an arithmetic number, because the mean of its divisors is an integer number (445735918551).

Almost surely, 2^{1781199109901} is an apocalyptic number.

It is an amenable number.

1781199109901 is a deficient number, since it is larger than the sum of its proper divisors (1744564303).

1781199109901 is a wasteful number, since it uses less digits than its factorization.

1781199109901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1744564302.

The product of its (nonzero) digits is 367416, while the sum is 56.

The spelling of 1781199109901 in words is "one trillion, seven hundred eighty-one billion, one hundred ninety-nine million, one hundred nine thousand, nine hundred one".