1221140021 has 2 divisors, whose sum is σ = 1221140022. Its totient is φ = 1221140020.

The previous prime is 1221140017. The next prime is 1221140027. The reversal of 1221140021 is 1200411221.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1150159396 + 70980625 = 33914^2 + 8425^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221140021 - 2² = 1221140017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221139978 and 1221140005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221140027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610570010 + 610570011.

It is an arithmetic number, because the mean of its divisors is an integer number (610570011).

Almost surely, 2^1221140021 is an apocalyptic number.

It is an amenable number.

1221140021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221140021 is an equidigital number, since it uses as much as digits as its factorization.

1221140021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 1221140021 is about 34944.8139356901. The cubic root of 1221140021 is about 1068.8624533999.

Adding to 1221140021 its reverse (1200411221), we get a palindrome (2421551242).

The spelling of 1221140021 in words is "one billion, two hundred twenty-one million, one hundred forty thousand, twenty-one".