1787978941 has 4 divisors (see below), whose sum is σ = 2043404512. Its totient is φ = 1532553372.

The previous prime is 1787978921. The next prime is 1787978947. The reversal of 1787978941 is 1498797871.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1498797871 = 761 ⋅1969511.

It is not a de Polignac number, because 1787978941 - 2⁷ = 1787978813 is a prime.

It is the 42285-th Hogben number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1787978941.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1787978947) by changing a digit.

It is a nontrivial repunit in base 42284.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 127712775 + ... + 127712788.

It is an arithmetic number, because the mean of its divisors is an integer number (510851128).

Almost surely, 2^1787978941 is an apocalyptic number.

It is an amenable number.

1787978941 is a deficient number, since it is larger than the sum of its proper divisors (255425571).

1787978941 is an equidigital number, since it uses as much as digits as its factorization.

1787978941 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255425570.

The product of its digits is 7112448, while the sum is 61.

The square root of 1787978941 is about 42284.5000088685. The cubic root of 1787978941 is about 1213.7264036539.

The spelling of 1787978941 in words is "one billion, seven hundred eighty-seven million, nine hundred seventy-eight thousand, nine hundred forty-one".