1215649 has 2 divisors, whose sum is σ = 1215650. Its totient is φ = 1215648.

The previous prime is 1215647. The next prime is 1215673. The reversal of 1215649 is 9465121.

1215649 is nontrivially palindromic in base 4.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 893025 + 322624 = 945^2 + 568^2 .

It is a cyclic number.

It is not a de Polignac number, because 1215649 - 2¹ = 1215647 is a prime.

Together with 1215647, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1215647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607824 + 607825.

It is an arithmetic number, because the mean of its divisors is an integer number (607825).

2^1215649 is an apocalyptic number.

It is an amenable number.

1215649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215649 is an equidigital number, since it uses as much as digits as its factorization.

1215649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 28.

The square root of 1215649 is about 1102.5647373284. The cubic root of 1215649 is about 106.7257951253.

The spelling of 1215649 in words is "one million, two hundred fifteen thousand, six hundred forty-nine".