1861972897 has 2 divisors, whose sum is σ = 1861972898. Its totient is φ = 1861972896.

The previous prime is 1861972841. The next prime is 1861972901. The reversal of 1861972897 is 7982791681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1852785936 + 9186961 = 43044^2 + 3031^2 .

It is an emirp because it is prime and its reverse (7982791681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1861972897 - 2⁷ = 1861972769 is a prime.

It is not a weakly prime, because it can be changed into another prime (1861972817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 930986448 + 930986449.

It is an arithmetic number, because the mean of its divisors is an integer number (930986449).

Almost surely, 2^1861972897 is an apocalyptic number.

It is an amenable number.

1861972897 is a deficient number, since it is larger than the sum of its proper divisors (1).

1861972897 is an equidigital number, since it uses as much as digits as its factorization.

1861972897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3048192, while the sum is 58.

The square root of 1861972897 is about 43150.5839705559. The cubic root of 1861972897 is about 1230.2436111656.

The spelling of 1861972897 in words is "one billion, eight hundred sixty-one million, nine hundred seventy-two thousand, eight hundred ninety-seven".