1213421021 has 2 divisors, whose sum is σ = 1213421022. Its totient is φ = 1213421020.

The previous prime is 1213421017. The next prime is 1213421029. The reversal of 1213421021 is 1201243121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 676572121 + 536848900 = 26011^2 + 23170^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213421021 - 2² = 1213421017 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1213421029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606710510 + 606710511.

It is an arithmetic number, because the mean of its divisors is an integer number (606710511).

Almost surely, 2^1213421021 is an apocalyptic number.

It is an amenable number.

1213421021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213421021 is an equidigital number, since it uses as much as digits as its factorization.

1213421021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 1213421021 is about 34834.1932732768. The cubic root of 1213421021 is about 1066.6055473552.

Adding to 1213421021 its reverse (1201243121), we get a palindrome (2414664142).

The spelling of 1213421021 in words is "one billion, two hundred thirteen million, four hundred twenty-one thousand, twenty-one".