1556427027821 has 2 divisors, whose sum is σ = 1556427027822. Its totient is φ = 1556427027820.

The previous prime is 1556427027817. The next prime is 1556427027851. The reversal of 1556427027821 is 1287207246551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1407651738025 + 148775289796 = 1186445^2 + 385714^2 .

It is a cyclic number.

It is not a de Polignac number, because 1556427027821 - 2² = 1556427027817 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1556427027821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1556427027851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 778213513910 + 778213513911.

It is an arithmetic number, because the mean of its divisors is an integer number (778213513911).

Almost surely, 2^{1556427027821} is an apocalyptic number.

It is an amenable number.

1556427027821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1556427027821 is an equidigital number, since it uses as much as digits as its factorization.

1556427027821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1881600, while the sum is 50.

The spelling of 1556427027821 in words is "one trillion, five hundred fifty-six billion, four hundred twenty-seven million, twenty-seven thousand, eight hundred twenty-one".