1897981709 has 8 divisors (see below), whose sum is σ = 2056077240. Its totient is φ = 1751981088.

The previous prime is 1897981699. The next prime is 1897981739. The reversal of 1897981709 is 9071897981.

It can be written as a sum of positive squares in 4 ways, for example, as 358988809 + 1538992900 = 18947^2 + 39230^2 .

It is not a de Polignac number, because 1897981709 - 2⁸ = 1897981453 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 (1897981739) 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, 429752 + ... + 434145.

It is an arithmetic number, because the mean of its divisors is an integer number (257009655).

Almost surely, 2^1897981709 is an apocalyptic number.

It is an amenable number.

1897981709 is a deficient number, since it is larger than the sum of its proper divisors (158095531).

1897981709 is an frugal number, since it uses more digits than its factorization.

1897981709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 863936 (or 863910 counting only the distinct ones).

The product of its (nonzero) digits is 2286144, while the sum is 59.

The square root of 1897981709 is about 43565.8318984041. The cubic root of 1897981709 is about 1238.1236164964.

The spelling of 1897981709 in words is "one billion, eight hundred ninety-seven million, nine hundred eighty-one thousand, seven hundred nine".