191538397 has 4 divisors (see below), whose sum is σ = 193295740. Its totient is φ = 189781056.

The previous prime is 191538379. The next prime is 191538409. The reversal of 191538397 is 793835191.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 793835191 = 683 ⋅1162277.

It can be written as a sum of positive squares in 2 ways, for example, as 68128516 + 123409881 = 8254^2 + 11109^2 .

It is a cyclic number.

It is not a de Polignac number, because 191538397 - 2¹¹ = 191536349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191538377) 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, 878508 + ... + 878725.

It is an arithmetic number, because the mean of its divisors is an integer number (48323935).

Almost surely, 2^191538397 is an apocalyptic number.

It is an amenable number.

191538397 is a deficient number, since it is larger than the sum of its proper divisors (1757343).

191538397 is a wasteful number, since it uses less digits than its factorization.

191538397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1757342.

The product of its digits is 204120, while the sum is 46.

The square root of 191538397 is about 13839.7397735651. The cubic root of 191538397 is about 576.4371330065.

The spelling of 191538397 in words is "one hundred ninety-one million, five hundred thirty-eight thousand, three hundred ninety-seven".