155687891 has 2 divisors, whose sum is σ = 155687892. Its totient is φ = 155687890.

The previous prime is 155687879. The next prime is 155687927. The reversal of 155687891 is 198786551.

It is a weak prime.

It is an emirp because it is prime and its reverse (198786551) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155687891 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (155687491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77843945 + 77843946.

It is an arithmetic number, because the mean of its divisors is an integer number (77843946).

Almost surely, 2^155687891 is an apocalyptic number.

155687891 is a deficient number, since it is larger than the sum of its proper divisors (1).

155687891 is an equidigital number, since it uses as much as digits as its factorization.

155687891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 604800, while the sum is 50.

The square root of 155687891 is about 12477.4953816862. The cubic root of 155687891 is about 537.9620153021.

The spelling of 155687891 in words is "one hundred fifty-five million, six hundred eighty-seven thousand, eight hundred ninety-one".