155681609 has 4 divisors (see below), whose sum is σ = 155907600. Its totient is φ = 155455620.

The previous prime is 155681567. The next prime is 155681623. The reversal of 155681609 is 906186551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 155681609 - 2¹⁶ = 155616073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155681209) 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, 111959 + ... + 113340.

It is an arithmetic number, because the mean of its divisors is an integer number (38976900).

Almost surely, 2^155681609 is an apocalyptic number.

It is an amenable number.

155681609 is a deficient number, since it is larger than the sum of its proper divisors (225991).

155681609 is an equidigital number, since it uses as much as digits as its factorization.

155681609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225990.

The product of its (nonzero) digits is 64800, while the sum is 41.

The square root of 155681609 is about 12477.2436459340. The cubic root of 155681609 is about 537.9547796231.

The spelling of 155681609 in words is "one hundred fifty-five million, six hundred eighty-one thousand, six hundred nine".