1391521821823 has 12 divisors (see below), whose sum is σ = 1618731970272. Its totient is φ = 1192716107520.

The previous prime is 1391521821803. The next prime is 1391521821961. The reversal of 1391521821823 is 3281281251931.

It is a de Polignac number, because none of the positive numbers 2^k-1391521821823 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 (1391521821803) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4326138 + ... + 4636648.

It is an arithmetic number, because the mean of its divisors is an integer number (134894330856).

Almost surely, 2^{1391521821823} is an apocalyptic number.

1391521821823 is a deficient number, since it is larger than the sum of its proper divisors (227210148449).

1391521821823 is an equidigital number, since it uses as much as digits as its factorization.

1391521821823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401982 (or 401975 counting only the distinct ones).

The product of its digits is 207360, while the sum is 46.

The spelling of 1391521821823 in words is "one trillion, three hundred ninety-one billion, five hundred twenty-one million, eight hundred twenty-one thousand, eight hundred twenty-three".