191820661772 has 12 divisors (see below), whose sum is σ = 342828417120. Its totient is φ = 93869685456.

The previous prime is 191820661759. The next prime is 191820661777. The reversal of 191820661772 is 277166028191.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 191820661772.

It is not an unprimeable number, because it can be changed into a prime (191820661777) 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, 510161147 + ... + 510161522.

It is an arithmetic number, because the mean of its divisors is an integer number (28569034760).

Almost surely, 2^191820661772 is an apocalyptic number.

It is an amenable number.

191820661772 is a deficient number, since it is larger than the sum of its proper divisors (151007755348).

191820661772 is a wasteful number, since it uses less digits than its factorization.

191820661772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1020322720 (or 1020322718 counting only the distinct ones).

The product of its (nonzero) digits is 508032, while the sum is 50.

The spelling of 191820661772 in words is "one hundred ninety-one billion, eight hundred twenty million, six hundred sixty-one thousand, seven hundred seventy-two".