155506391 has 2 divisors, whose sum is σ = 155506392. Its totient is φ = 155506390.

The previous prime is 155506349. The next prime is 155506433. The reversal of 155506391 is 193605551.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (155506349) and next prime (155506433).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155506391 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155506591) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77753195 + 77753196.

It is an arithmetic number, because the mean of its divisors is an integer number (77753196).

Almost surely, 2^155506391 is an apocalyptic number.

155506391 is a deficient number, since it is larger than the sum of its proper divisors (1).

155506391 is an equidigital number, since it uses as much as digits as its factorization.

155506391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20250, while the sum is 35.

The square root of 155506391 is about 12470.2201664606. The cubic root of 155506391 is about 537.7528830601.

The spelling of 155506391 in words is "one hundred fifty-five million, five hundred six thousand, three hundred ninety-one".