1997154091 has 4 divisors (see below), whose sum is σ = 2029894384. Its totient is φ = 1964413800.

The previous prime is 1997154083. The next prime is 1997154119. The reversal of 1997154091 is 1904517991.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1997154091 - 2³ = 1997154083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1997154031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16370055 + ... + 16370176.

It is an arithmetic number, because the mean of its divisors is an integer number (507473596).

Almost surely, 2^1997154091 is an apocalyptic number.

1997154091 is a deficient number, since it is larger than the sum of its proper divisors (32740293).

1997154091 is an equidigital number, since it uses as much as digits as its factorization.

1997154091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32740292.

The product of its (nonzero) digits is 102060, while the sum is 46.

The square root of 1997154091 is about 44689.5299930532. The cubic root of 1997154091 is about 1259.3231627739.

The spelling of 1997154091 in words is "one billion, nine hundred ninety-seven million, one hundred fifty-four thousand, ninety-one".