155811961 has 4 divisors (see below), whose sum is σ = 156283024. Its totient is φ = 155340900.

The previous prime is 155811947. The next prime is 155811977. The reversal of 155811961 is 169118551.

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 155811961 - 2⁹ = 155811449 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 155811961.

It is not an unprimeable number, because it can be changed into a prime (155811941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 235035 + ... + 235696.

It is an arithmetic number, because the mean of its divisors is an integer number (39070756).

Almost surely, 2^155811961 is an apocalyptic number.

It is an amenable number.

155811961 is a deficient number, since it is larger than the sum of its proper divisors (471063).

155811961 is an equidigital number, since it uses as much as digits as its factorization.

155811961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 471062.

The product of its digits is 10800, while the sum is 37.

The square root of 155811961 is about 12482.4661425537. The cubic root of 155811961 is about 538.1048806734.

The spelling of 155811961 in words is "one hundred fifty-five million, eight hundred eleven thousand, nine hundred sixty-one".