1997942891 has 8 divisors (see below), whose sum is σ = 2403540480. Its totient is φ = 1622389608.

The previous prime is 1997942887. The next prime is 1997942897. The reversal of 1997942891 is 1982497991.

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

It is not a de Polignac number, because 1997942891 - 2² = 1997942887 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1997942891.

It is not an unprimeable number, because it can be changed into a prime (1997942897) 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, 7510931 + ... + 7511196.

It is an arithmetic number, because the mean of its divisors is an integer number (300442560).

Almost surely, 2^1997942891 is an apocalyptic number.

1997942891 is a deficient number, since it is larger than the sum of its proper divisors (405597589).

1997942891 is a wasteful number, since it uses less digits than its factorization.

1997942891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15022153.

The product of its digits is 2939328, while the sum is 59.

The square root of 1997942891 is about 44698.3544551698. The cubic root of 1997942891 is about 1259.4889358882.

Subtracting from 1997942891 its reverse (1982497991), we obtain a square (15444900 = 3930²).

The spelling of 1997942891 in words is "one billion, nine hundred ninety-seven million, nine hundred forty-two thousand, eight hundred ninety-one".