145091991 has 16 divisors (see below), whose sum is σ = 223458048. Its totient is φ = 82761600.

The previous prime is 145091963. The next prime is 145091993. The reversal of 145091991 is 199190541.

It is not a de Polignac number, because 145091991 - 2⁶ = 145091927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (145091993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 128755 + ... + 129876.

It is an arithmetic number, because the mean of its divisors is an integer number (13966128).

Almost surely, 2^145091991 is an apocalyptic number.

145091991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

145091991 is a deficient number, since it is larger than the sum of its proper divisors (78366057).

145091991 is a wasteful number, since it uses less digits than its factorization.

145091991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258662.

The product of its (nonzero) digits is 14580, while the sum is 39.

The square root of 145091991 is about 12045.4136915259. The cubic root of 145091991 is about 525.4698632577.

The spelling of 145091991 in words is "one hundred forty-five million, ninety-one thousand, nine hundred ninety-one".