1897712857 has 4 divisors (see below), whose sum is σ = 1897801780. Its totient is φ = 1897623936.

The previous prime is 1897712849. The next prime is 1897712863. The reversal of 1897712857 is 7582177981.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1790051481 + 107661376 = 42309^2 + 10376^2 .

It is a 3-Lehmer number, since φ(1897712857) divides (1897712857-1)³.

It is a cyclic number.

It is not a de Polignac number, because 1897712857 - 2³ = 1897712849 is a prime.

It is a deceptive number, since it divides R_1897712856.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1897712798 and 1897712807.

It is not an unprimeable number, because it can be changed into a prime (1897712827) 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, 8893 + ... + 62245.

It is an arithmetic number, because the mean of its divisors is an integer number (474450445).

Almost surely, 2^1897712857 is an apocalyptic number.

1897712857 is the 35569-th pentagonal number.

It is an amenable number.

1897712857 is a deficient number, since it is larger than the sum of its proper divisors (88923).

1897712857 is an equidigital number, since it uses as much as digits as its factorization.

1897712857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88922.

The product of its digits is 1975680, while the sum is 55.

The square root of 1897712857 is about 43562.7462059040. The cubic root of 1897712857 is about 1238.0651530371.

The spelling of 1897712857 in words is "one billion, eight hundred ninety-seven million, seven hundred twelve thousand, eight hundred fifty-seven".