1213111021 has 2 divisors, whose sum is σ = 1213111022. Its totient is φ = 1213111020.

The previous prime is 1213110989. The next prime is 1213111033. The reversal of 1213111021 is 1201113121.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1037548521 + 175562500 = 32211^2 + 13250^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213111021 - 2⁵ = 1213110989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1213110992 and 1213111010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1213111061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606555510 + 606555511.

It is an arithmetic number, because the mean of its divisors is an integer number (606555511).

Almost surely, 2^1213111021 is an apocalyptic number.

It is an amenable number.

1213111021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213111021 is an equidigital number, since it uses as much as digits as its factorization.

1213111021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12, while the sum is 13.

The square root of 1213111021 is about 34829.7433381298. The cubic root of 1213111021 is about 1066.5147088978.

Adding to 1213111021 its reverse (1201113121), we get a palindrome (2414224142).

The spelling of 1213111021 in words is "one billion, two hundred thirteen million, one hundred eleven thousand, twenty-one".