1213921 has 2 divisors, whose sum is σ = 1213922. Its totient is φ = 1213920.

The previous prime is 1213913. The next prime is 1213931. The reversal of 1213921 is 1293121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1073296 + 140625 = 1036^2 + 375^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213921 - 2³ = 1213913 is a prime.

It is an Ulam number.

1213921 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1213931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606960 + 606961.

It is an arithmetic number, because the mean of its divisors is an integer number (606961).

2^1213921 is an apocalyptic number.

It is an amenable number.

1213921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213921 is an equidigital number, since it uses as much as digits as its factorization.

1213921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108, while the sum is 19.

The square root of 1213921 is about 1101.7808312001. The cubic root of 1213921 is about 106.6752022249.

The spelling of 1213921 in words is "one million, two hundred thirteen thousand, nine hundred twenty-one".