1978744677917 has 4 divisors (see below), whose sum is σ = 2261422489056. Its totient is φ = 1696066866780.

The previous prime is 1978744677901. The next prime is 1978744677979. The reversal of 1978744677917 is 7197764478791.

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 1978744677917 - 2⁴ = 1978744677901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978744677317) 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, 141338905559 + ... + 141338905572.

It is an arithmetic number, because the mean of its divisors is an integer number (565355622264).

Almost surely, 2^{1978744677917} is an apocalyptic number.

It is an amenable number.

1978744677917 is a deficient number, since it is larger than the sum of its proper divisors (282677811139).

1978744677917 is an equidigital number, since it uses as much as digits as its factorization.

1978744677917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282677811138.

The product of its digits is 1045529856, while the sum is 77.

The spelling of 1978744677917 in words is "one trillion, nine hundred seventy-eight billion, seven hundred forty-four million, six hundred seventy-seven thousand, nine hundred seventeen".