1391406638 has 8 divisors (see below), whose sum is σ = 2088124920. Its totient is φ = 695365000.

The previous prime is 1391406619. The next prime is 1391406647. The reversal of 1391406638 is 8366041931.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 1391406595 and 1391406604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 163988 + ... + 172263.

It is an arithmetic number, because the mean of its divisors is an integer number (261015615).

Almost surely, 2^1391406638 is an apocalyptic number.

1391406638 is a deficient number, since it is larger than the sum of its proper divisors (696718282).

1391406638 is a wasteful number, since it uses less digits than its factorization.

1391406638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338322.

The product of its (nonzero) digits is 93312, while the sum is 41.

The square root of 1391406638 is about 37301.5634792967. The cubic root of 1391406638 is about 1116.3953621828.

The spelling of 1391406638 in words is "one billion, three hundred ninety-one million, four hundred six thousand, six hundred thirty-eight".