154891991 has 2 divisors, whose sum is σ = 154891992. Its totient is φ = 154891990.

The previous prime is 154891969. The next prime is 154892011. The reversal of 154891991 is 199198451.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 154891991 - 2²⁶ = 87783127 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (154891391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77445995 + 77445996.

It is an arithmetic number, because the mean of its divisors is an integer number (77445996).

Almost surely, 2^154891991 is an apocalyptic number.

154891991 is a deficient number, since it is larger than the sum of its proper divisors (1).

154891991 is an equidigital number, since it uses as much as digits as its factorization.

154891991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 47.

The square root of 154891991 is about 12445.5610962303. The cubic root of 154891991 is about 537.0437343803.

It can be divided in two parts, 1548 and 91991, that added together give a palindrome (93539).

The spelling of 154891991 in words is "one hundred fifty-four million, eight hundred ninety-one thousand, nine hundred ninety-one".