1215521 has 2 divisors, whose sum is σ = 1215522. Its totient is φ = 1215520.

The previous prime is 1215509. The next prime is 1215553. The reversal of 1215521 is 1255121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 929296 + 286225 = 964^2 + 535^2 .

It is a cyclic number.

It is not a de Polignac number, because 1215521 - 2⁶ = 1215457 is a prime.

It is a Chen prime.

It is equal to p₉₄₀₃₁ and since 1215521 and 94031 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1215521.

It is not a weakly prime, because it can be changed into another prime (1215121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607760 + 607761.

It is an arithmetic number, because the mean of its divisors is an integer number (607761).

2^1215521 is an apocalyptic number.

It is an amenable number.

1215521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215521 is an equidigital number, since it uses as much as digits as its factorization.

1215521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100, while the sum is 17.

The square root of 1215521 is about 1102.5066893221. The cubic root of 1215521 is about 106.7220491478.

It can be divided in two parts, 12155 and 21, that multiplied together give a triangular number (255255 = T₇₁₄).

The spelling of 1215521 in words is "one million, two hundred fifteen thousand, five hundred twenty-one".