1908909216661 has 4 divisors (see below), whose sum is σ = 1912096044000. Its totient is φ = 1905722389324.

The previous prime is 1908909216623. The next prime is 1908909216689. The reversal of 1908909216661 is 1666129098091.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1908909216661 - 2³¹ = 1906761733013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1908909216596 and 1908909216605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1908909210661) 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, 1593412771 + ... + 1593413968.

It is an arithmetic number, because the mean of its divisors is an integer number (478024011000).

Almost surely, 2^{1908909216661} is an apocalyptic number.

It is an amenable number.

1908909216661 is a deficient number, since it is larger than the sum of its proper divisors (3186827339).

1908909216661 is an equidigital number, since it uses as much as digits as its factorization.

1908909216661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3186827338.

The product of its (nonzero) digits is 2519424, while the sum is 58.

The spelling of 1908909216661 in words is "one trillion, nine hundred eight billion, nine hundred nine million, two hundred sixteen thousand, six hundred sixty-one".