1320421535551 has 4 divisors (see below), whose sum is σ = 1320894977400. Its totient is φ = 1319948093704.

The previous prime is 1320421535539. The next prime is 1320421535569. The reversal of 1320421535551 is 1555351240231.

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

It is a cyclic number.

It is not a de Polignac number, because 1320421535551 - 2⁵ = 1320421535519 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 1320421535551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1320428535551) 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, 236716741 + ... + 236722318.

It is an arithmetic number, because the mean of its divisors is an integer number (330223744350).

Almost surely, 2^{1320421535551} is an apocalyptic number.

1320421535551 is a deficient number, since it is larger than the sum of its proper divisors (473441849).

1320421535551 is an equidigital number, since it uses as much as digits as its factorization.

1320421535551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473441848.

The product of its (nonzero) digits is 90000, while the sum is 37.

Adding to 1320421535551 its reverse (1555351240231), we get a palindrome (2875772775782).

The spelling of 1320421535551 in words is "one trillion, three hundred twenty billion, four hundred twenty-one million, five hundred thirty-five thousand, five hundred fifty-one".