154991 has 2 divisors, whose sum is σ = 154992. Its totient is φ = 154990.

The previous prime is 154981. The next prime is 155003. The reversal of 154991 is 199451.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 154991 - 2⁶ = 154927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (154981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77495 + 77496.

It is an arithmetic number, because the mean of its divisors is an integer number (77496).

2¹⁵⁴⁹⁹¹ is an apocalyptic number.

154991 is a deficient number, since it is larger than the sum of its proper divisors (1).

154991 is an equidigital number, since it uses as much as digits as its factorization.

154991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 29.

The square root of 154991 is about 393.6889635232. The cubic root of 154991 is about 53.7158138483.

The spelling of 154991 in words is "one hundred fifty-four thousand, nine hundred ninety-one".