155727661 has 4 divisors (see below), whose sum is σ = 157477500. Its totient is φ = 153977824.

The previous prime is 155727653. The next prime is 155727683. The reversal of 155727661 is 166727551.

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: 166727551 = 17 ⋅9807503.

It can be written as a sum of positive squares in 2 ways, for example, as 63202500 + 92525161 = 7950^2 + 9619^2 .

It is a cyclic number.

It is not a de Polignac number, because 155727661 - 2³ = 155727653 is a prime.

It is a super-2 number, since 2×155727661² = 48502208801061842, which 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 (155787661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 874786 + ... + 874963.

It is an arithmetic number, because the mean of its divisors is an integer number (39369375).

Almost surely, 2^155727661 is an apocalyptic number.

It is an amenable number.

155727661 is a deficient number, since it is larger than the sum of its proper divisors (1749839).

155727661 is an equidigital number, since it uses as much as digits as its factorization.

155727661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1749838.

The product of its digits is 88200, while the sum is 40.

The square root of 155727661 is about 12479.0889491180. The cubic root of 155727661 is about 538.0078183245.

The spelling of 155727661 in words is "one hundred fifty-five million, seven hundred twenty-seven thousand, six hundred sixty-one".