139751391821 has 4 divisors (see below), whose sum is σ = 139752152892. Its totient is φ = 139750630752.

The previous prime is 139751391817. The next prime is 139751391851. The reversal of 139751391821 is 128193157931.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 128193157931 = 8419 ⋅15226649.

It can be written as a sum of positive squares in 2 ways, for example, as 39253515625 + 100497876196 = 198125^2 + 317014^2 .

It is a cyclic number.

It is not a de Polignac number, because 139751391821 - 2² = 139751391817 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 139751391821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (139751391811) 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, 83615 + ... + 535251.

It is an arithmetic number, because the mean of its divisors is an integer number (34938038223).

Almost surely, 2^139751391821 is an apocalyptic number.

It is an amenable number.

139751391821 is a deficient number, since it is larger than the sum of its proper divisors (761071).

139751391821 is an equidigital number, since it uses as much as digits as its factorization.

139751391821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 761070.

The product of its digits is 408240, while the sum is 50.

The spelling of 139751391821 in words is "one hundred thirty-nine billion, seven hundred fifty-one million, three hundred ninety-one thousand, eight hundred twenty-one".