3998320901557 has 2 divisors, whose sum is σ = 3998320901558. Its totient is φ = 3998320901556.

The previous prime is 3998320901551. The next prime is 3998320901581. The reversal of 3998320901557 is 7551090238993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2980978355601 + 1017342545956 = 1726551^2 + 1008634^2 .

It is a cyclic number.

It is not a de Polignac number, because 3998320901557 - 2⁷ = 3998320901429 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 3998320901495 and 3998320901504.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3998320901551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1999160450778 + 1999160450779.

It is an arithmetic number, because the mean of its divisors is an integer number (1999160450779).

Almost surely, 2^{3998320901557} is an apocalyptic number.

It is an amenable number.

3998320901557 is a deficient number, since it is larger than the sum of its proper divisors (1).

3998320901557 is an equidigital number, since it uses as much as digits as its factorization.

3998320901557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18370800, while the sum is 61.

The spelling of 3998320901557 in words is "three trillion, nine hundred ninety-eight billion, three hundred twenty million, nine hundred one thousand, five hundred fifty-seven".