1391221931 has 8 divisors (see below), whose sum is σ = 1518061824. Its totient is φ = 1264442920.

The previous prime is 1391221921. The next prime is 1391221939.

It is a happy number.

1391221931 is nontrivially palindromic in base 10.

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

It is a cyclic number.

It is not a de Polignac number, because 1391221931 - 2²⁶ = 1324113067 is a prime.

It is a super-2 number, since 2×1391221931² = 3870996922590737522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1391221939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41906 + ... + 67368.

It is an arithmetic number, because the mean of its divisors is an integer number (189757728).

Almost surely, 2^1391221931 is an apocalyptic number.

1391221931 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1391221931 is a deficient number, since it is larger than the sum of its proper divisors (126839893).

1391221931 is a wasteful number, since it uses less digits than its factorization.

1391221931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30441.

The product of its digits is 2916, while the sum is 32.

The square root of 1391221931 is about 37299.0875357562. The cubic root of 1391221931 is about 1116.3459600986.

It can be divided in two parts, 1391 and 221931, that added together give a palindrome (223322).

The spelling of 1391221931 in words is "one billion, three hundred ninety-one million, two hundred twenty-one thousand, nine hundred thirty-one".