1321657 has 2 divisors, whose sum is σ = 1321658. Its totient is φ = 1321656.

The previous prime is 1321651. The next prime is 1321669. The reversal of 1321657 is 7561231.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1297321 + 24336 = 1139^2 + 156^2 .

It is an emirp because it is prime and its reverse (7561231) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1321657 - 2¹¹ = 1319609 is a prime.

It is not a weakly prime, because it can be changed into another prime (1321651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660828 + 660829.

It is an arithmetic number, because the mean of its divisors is an integer number (660829).

2^1321657 is an apocalyptic number.

It is an amenable number.

1321657 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321657 is an equidigital number, since it uses as much as digits as its factorization.

1321657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1260, while the sum is 25.

The square root of 1321657 is about 1149.6334198343. The cubic root of 1321657 is about 109.7420124842.

Adding to 1321657 its reverse (7561231), we get a palindrome (8882888).

The spelling of 1321657 in words is "one million, three hundred twenty-one thousand, six hundred fifty-seven".