155661977 has 2 divisors, whose sum is σ = 155661978. Its totient is φ = 155661976.

The previous prime is 155661973. The next prime is 155661983. The reversal of 155661977 is 779166551.

155661977 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 154231561 + 1430416 = 12419^2 + 1196^2 .

It is an emirp because it is prime and its reverse (779166551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 155661977 - 2² = 155661973 is a prime.

It is not a weakly prime, because it can be changed into another prime (155661973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77830988 + 77830989.

It is an arithmetic number, because the mean of its divisors is an integer number (77830989).

Almost surely, 2^155661977 is an apocalyptic number.

It is an amenable number.

155661977 is a deficient number, since it is larger than the sum of its proper divisors (1).

155661977 is an equidigital number, since it uses as much as digits as its factorization.

155661977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 396900, while the sum is 47.

The square root of 155661977 is about 12476.4569089145. The cubic root of 155661977 is about 537.9321660074.

The spelling of 155661977 in words is "one hundred fifty-five million, six hundred sixty-one thousand, nine hundred seventy-seven".