191397978001 has 4 divisors (see below), whose sum is σ = 191400206004. Its totient is φ = 191395750000.

The previous prime is 191397977987. The next prime is 191397978017. The reversal of 191397978001 is 100879793191.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 100879793191 = 1609 ⋅62697199.

It can be written as a sum of positive squares in 2 ways, for example, as 157144852225 + 34253125776 = 396415^2 + 185076^2 .

It is a cyclic number.

It is not a de Polignac number, because 191397978001 - 2⁷ = 191397977873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191397978041) 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, 979750 + ... + 1158751.

It is an arithmetic number, because the mean of its divisors is an integer number (47850051501).

Almost surely, 2^191397978001 is an apocalyptic number.

It is an amenable number.

191397978001 is a deficient number, since it is larger than the sum of its proper divisors (2228003).

191397978001 is an equidigital number, since it uses as much as digits as its factorization.

191397978001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2228002.

The product of its (nonzero) digits is 857304, while the sum is 55.

The spelling of 191397978001 in words is "one hundred ninety-one billion, three hundred ninety-seven million, nine hundred seventy-eight thousand, one".