135291991 has 8 divisors (see below), whose sum is σ = 140120064. Its totient is φ = 130545240.

The previous prime is 135291973. The next prime is 135292013. The reversal of 135291991 is 199192531.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 135291991 - 2¹¹ = 135289943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (135291901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16935 + ... + 23608.

It is an arithmetic number, because the mean of its divisors is an integer number (17515008).

Almost surely, 2^135291991 is an apocalyptic number.

135291991 is a deficient number, since it is larger than the sum of its proper divisors (4828073).

135291991 is an equidigital number, since it uses as much as digits as its factorization.

135291991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40661.

The product of its digits is 21870, while the sum is 40.

The square root of 135291991 is about 11631.5085436069. The cubic root of 135291991 is about 513.3623677380.

The spelling of 135291991 in words is "one hundred thirty-five million, two hundred ninety-one thousand, nine hundred ninety-one".