1215421 has 2 divisors, whose sum is σ = 1215422. Its totient is φ = 1215420.

The previous prime is 1215407. The next prime is 1215433. The reversal of 1215421 is 1245121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 622521 + 592900 = 789^2 + 770^2 .

It is an emirp because it is prime and its reverse (1245121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1215421 - 2⁹ = 1214909 is a prime.

It is equal to p₉₄₀₂₁ and since 1215421 and 94021 have the same sum of digits, it is a Honaker prime.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 1215395 and 1215404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1215451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607710 + 607711.

It is an arithmetic number, because the mean of its divisors is an integer number (607711).

2^1215421 is an apocalyptic number.

It is an amenable number.

1215421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215421 is an equidigital number, since it uses as much as digits as its factorization.

1215421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80, while the sum is 16.

The square root of 1215421 is about 1102.4613371906. The cubic root of 1215421 is about 106.7191224200.

The spelling of 1215421 in words is "one million, two hundred fifteen thousand, four hundred twenty-one".