1891020069 has 12 divisors (see below), whose sum is σ = 2776252492. Its totient is φ = 1240012800.

The previous prime is 1891020059. The next prime is 1891020091. The reversal of 1891020069 is 9600201981.

It can be written as a sum of positive squares in 2 ways, for example, as 38750625 + 1852269444 = 6225^2 + 43038^2 .

It is not a de Polignac number, because 1891020069 - 2¹¹ = 1891018021 is a prime.

It is a super-2 number, since 2×1891020069² = 7151913802721529522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1891020029) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1721692 + ... + 1722789.

Almost surely, 2^1891020069 is an apocalyptic number.

It is an amenable number.

1891020069 is a deficient number, since it is larger than the sum of its proper divisors (885232423).

1891020069 is a wasteful number, since it uses less digits than its factorization.

1891020069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3444548 (or 3444545 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 1891020069 is about 43485.8605640960. The cubic root of 1891020069 is about 1236.6079835550.

The spelling of 1891020069 in words is "one billion, eight hundred ninety-one million, twenty thousand, sixty-nine".