1391947517 has 4 divisors (see below), whose sum is σ = 1396481856. Its totient is φ = 1387413180.

The previous prime is 1391947507. The next prime is 1391947519. The reversal of 1391947517 is 7157491931.

It is a happy number.

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 1391947517 - 2²⁶ = 1324838653 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 (1391947519) 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, 2266709 + ... + 2267322.

It is an arithmetic number, because the mean of its divisors is an integer number (349120464).

Almost surely, 2^1391947517 is an apocalyptic number.

It is an amenable number.

1391947517 is a deficient number, since it is larger than the sum of its proper divisors (4534339).

1391947517 is an equidigital number, since it uses as much as digits as its factorization.

1391947517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4534338.

The product of its digits is 238140, while the sum is 47.

The square root of 1391947517 is about 37308.8128596984. The cubic root of 1391947517 is about 1116.5400015630.

The spelling of 1391947517 in words is "one billion, three hundred ninety-one million, nine hundred forty-seven thousand, five hundred seventeen".