1897772777981 has 4 divisors (see below), whose sum is σ = 1916197756512. Its totient is φ = 1879347799452.

The previous prime is 1897772777947. The next prime is 1897772778037.

1897772777981 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1897772777981 - 2³⁴ = 1880592908797 is a prime.

It is a super-2 number, since 2×1897772777981² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1897772777896 and 1897772777905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1897772777881) 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, 9212489111 + ... + 9212489316.

It is an arithmetic number, because the mean of its divisors is an integer number (479049439128).

Almost surely, 2^{1897772777981} is an apocalyptic number.

It is an amenable number.

1897772777981 is a deficient number, since it is larger than the sum of its proper divisors (18424978531).

1897772777981 is a wasteful number, since it uses less digits than its factorization.

1897772777981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18424978530.

The product of its digits is 1219784832, while the sum is 80.

The spelling of 1897772777981 in words is "one trillion, eight hundred ninety-seven billion, seven hundred seventy-two million, seven hundred seventy-seven thousand, nine hundred eighty-one".