1555997 has 2 divisors, whose sum is σ = 1555998. Its totient is φ = 1555996.

The previous prime is 1555969. The next prime is 1555999. The reversal of 1555997 is 7995551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1552516 + 3481 = 1246^2 + 59^2 .

It is a cyclic number.

It is not a de Polignac number, because 1555997 - 2¹⁴ = 1539613 is a prime.

It is a super-2 number, since 2×1555997² = 4842253328018, which contains 22 as substring.

Together with 1555999, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1555999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777998 + 777999.

It is an arithmetic number, because the mean of its divisors is an integer number (777999).

2^1555997 is an apocalyptic number.

It is an amenable number.

1555997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555997 is an equidigital number, since it uses as much as digits as its factorization.

1555997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 70875, while the sum is 41.

The square root of 1555997 is about 1247.3960878566. The cubic root of 1555997 is about 115.8785143118.

It can be divided in two parts, 1555 and 997, that added together give a palindrome (2552).

The spelling of 1555997 in words is "one million, five hundred fifty-five thousand, nine hundred ninety-seven".