155851368661 has 4 divisors (see below), whose sum is σ = 160063567852. Its totient is φ = 151639169472.

The previous prime is 155851368643. The next prime is 155851368667. The reversal of 155851368661 is 166863158551.

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 148904146161 + 6947222500 = 385881^2 + 83350^2 .

It is a cyclic number.

It is not a de Polignac number, because 155851368661 - 2¹¹ = 155851366613 is a prime.

It is a super-2 number, since 2×155851368661² (a number of 23 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 (155851368667) 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, 2106099540 + ... + 2106099613.

It is an arithmetic number, because the mean of its divisors is an integer number (40015891963).

Almost surely, 2^155851368661 is an apocalyptic number.

It is an amenable number.

155851368661 is a deficient number, since it is larger than the sum of its proper divisors (4212199191).

155851368661 is an equidigital number, since it uses as much as digits as its factorization.

155851368661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4212199190.

The product of its digits is 5184000, while the sum is 55.

The spelling of 155851368661 in words is "one hundred fifty-five billion, eight hundred fifty-one million, three hundred sixty-eight thousand, six hundred sixty-one".