1391918917 has 4 divisors (see below), whose sum is σ = 1392055840. Its totient is φ = 1391781996.

The previous prime is 1391918897. The next prime is 1391918953. The reversal of 1391918917 is 7198191931.

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: 7198191931 = 7 ⋅1028313133.

It is a cyclic number.

It is not a de Polignac number, because 1391918917 - 2¹⁹ = 1391394629 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 (1391918977) 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, 51873 + ... + 73990.

It is an arithmetic number, because the mean of its divisors is an integer number (348013960).

Almost surely, 2^1391918917 is an apocalyptic number.

It is an amenable number.

1391918917 is a deficient number, since it is larger than the sum of its proper divisors (136923).

1391918917 is a wasteful number, since it uses less digits than its factorization.

1391918917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136922.

The product of its digits is 122472, while the sum is 49.

The square root of 1391918917 is about 37308.4295702727. The cubic root of 1391918917 is about 1116.5323544206.

The spelling of 1391918917 in words is "one billion, three hundred ninety-one million, nine hundred eighteen thousand, nine hundred seventeen".