1997447991 has 16 divisors (see below), whose sum is σ = 3320433408. Its totient is φ = 1037635200.

The previous prime is 1997447981. The next prime is 1997448049.

1997447991 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1997447991 - 2⁶ = 1997447927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1997447981) 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, 4323250 + ... + 4323711.

It is an arithmetic number, because the mean of its divisors is an integer number (207527088).

Almost surely, 2^1997447991 is an apocalyptic number.

1997447991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1997447991 is a deficient number, since it is larger than the sum of its proper divisors (1322985417).

1997447991 is a wasteful number, since it uses less digits than its factorization.

1997447991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8646982.

The product of its digits is 5143824, while the sum is 60.

The square root of 1997447991 is about 44692.8181143235. The cubic root of 1997447991 is about 1259.3849334914.

The spelling of 1997447991 in words is "one billion, nine hundred ninety-seven million, four hundred forty-seven thousand, nine hundred ninety-one".