149909891 has 2 divisors, whose sum is σ = 149909892. Its totient is φ = 149909890.

The previous prime is 149909873. The next prime is 149909941. The reversal of 149909891 is 198909941.

It is an a-pointer prime, because the next prime (149909941) can be obtained adding 149909891 to its sum of digits (50).

It is a weak prime.

It is an emirp because it is prime and its reverse (198909941) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 149909891 - 2⁶ = 149909827 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (149909191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 74954945 + 74954946.

It is an arithmetic number, because the mean of its divisors is an integer number (74954946).

Almost surely, 2^149909891 is an apocalyptic number.

149909891 is a deficient number, since it is larger than the sum of its proper divisors (1).

149909891 is an equidigital number, since it uses as much as digits as its factorization.

149909891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 209952, while the sum is 50.

The square root of 149909891 is about 12243.7694767584. The cubic root of 149909891 is about 531.2228687228. Note that the first 3 decimals are identical.

Adding to 149909891 its sum of digits (50), we get a palindrome (149909941).

Subtracting 149909891 from its reverse (198909941), we obtain a triangular number (49000050 = T₉₈₉₉).

The spelling of 149909891 in words is "one hundred forty-nine million, nine hundred nine thousand, eight hundred ninety-one".