1978536695391 has 12 divisors (see below), whose sum is σ = 2857925830032. Its totient is φ = 1319006236416.

The previous prime is 1978536695383. The next prime is 1978536695437. The reversal of 1978536695391 is 1935966358791.

1978536695391 is a `hidden beast` number, since 1 + 9 + 7 + 85 + 3 + 6 + 6 + 9 + 539 + 1 = 666.

It is not a de Polignac number, because 1978536695391 - 2³ = 1978536695383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978536695321) 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, 814251 + ... + 2149436.

It is an arithmetic number, because the mean of its divisors is an integer number (238160485836).

Almost surely, 2^{1978536695391} is an apocalyptic number.

1978536695391 is a deficient number, since it is larger than the sum of its proper divisors (879389134641).

1978536695391 is a wasteful number, since it uses less digits than its factorization.

1978536695391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3037870 (or 3037867 counting only the distinct ones).

The product of its digits is 330674400, while the sum is 72.

The spelling of 1978536695391 in words is "one trillion, nine hundred seventy-eight billion, five hundred thirty-six million, six hundred ninety-five thousand, three hundred ninety-one".