155891261 has 2 divisors, whose sum is σ = 155891262. Its totient is φ = 155891260.

The previous prime is 155891251. The next prime is 155891273. The reversal of 155891261 is 162198551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 134676025 + 21215236 = 11605^2 + 4606^2 .

It is a cyclic number.

It is not a de Polignac number, because 155891261 - 2¹⁴ = 155874877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155891251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77945630 + 77945631.

It is an arithmetic number, because the mean of its divisors is an integer number (77945631).

Almost surely, 2^155891261 is an apocalyptic number.

It is an amenable number.

155891261 is a deficient number, since it is larger than the sum of its proper divisors (1).

155891261 is an equidigital number, since it uses as much as digits as its factorization.

155891261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21600, while the sum is 38.

The square root of 155891261 is about 12485.6421941364. The cubic root of 155891261 is about 538.1961541110.

The spelling of 155891261 in words is "one hundred fifty-five million, eight hundred ninety-one thousand, two hundred sixty-one".