1985765431 has 4 divisors (see below), whose sum is σ = 2138516632. Its totient is φ = 1833014232.

The previous prime is 1985765387. The next prime is 1985765447. The reversal of 1985765431 is 1345675891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1345675891 = 7 ⋅192239413.

It is a cyclic number.

It is not a de Polignac number, because 1985765431 - 2⁷ = 1985765303 is a prime.

It is a super-2 number, since 2×1985765431² = 7886528693909231522, 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 (1985765231) 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, 76375581 + ... + 76375606.

It is an arithmetic number, because the mean of its divisors is an integer number (534629158).

Almost surely, 2^1985765431 is an apocalyptic number.

1985765431 is a deficient number, since it is larger than the sum of its proper divisors (152751201).

1985765431 is a wasteful number, since it uses less digits than its factorization.

1985765431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152751200.

The product of its digits is 907200, while the sum is 49.

The square root of 1985765431 is about 44561.9280440153. The cubic root of 1985765431 is about 1256.9248581760.

The spelling of 1985765431 in words is "one billion, nine hundred eighty-five million, seven hundred sixty-five thousand, four hundred thirty-one".