1391921623 has 4 divisors (see below), whose sum is σ = 1398163648. Its totient is φ = 1385679600.

The previous prime is 1391921617. The next prime is 1391921681. The reversal of 1391921623 is 3261291931.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1391921623 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 (1391921693) 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, 3120678 + ... + 3121123.

It is an arithmetic number, because the mean of its divisors is an integer number (349540912).

Almost surely, 2^1391921623 is an apocalyptic number.

1391921623 is a deficient number, since it is larger than the sum of its proper divisors (6242025).

1391921623 is an equidigital number, since it uses as much as digits as its factorization.

1391921623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6242024.

The product of its digits is 17496, while the sum is 37.

The square root of 1391921623 is about 37308.4658355178. The cubic root of 1391921623 is about 1116.5330779624.

The spelling of 1391921623 in words is "one billion, three hundred ninety-one million, nine hundred twenty-one thousand, six hundred twenty-three".