1243201021 has 4 divisors (see below), whose sum is σ = 1255510044. Its totient is φ = 1230892000.

The previous prime is 1243200979. The next prime is 1243201049. The reversal of 1243201021 is 1201023421.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1141493796 + 101707225 = 33786^2 + 10085^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243201021 - 2⁹ = 1243200509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1243200986 and 1243201004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1243201061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6154360 + ... + 6154561.

It is an arithmetic number, because the mean of its divisors is an integer number (313877511).

Almost surely, 2^1243201021 is an apocalyptic number.

It is an amenable number.

1243201021 is a deficient number, since it is larger than the sum of its proper divisors (12309023).

1243201021 is a wasteful number, since it uses less digits than its factorization.

1243201021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12309022.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 1243201021 is about 35259.0558722153. The cubic root of 1243201021 is about 1075.2607324297.

Adding to 1243201021 its reverse (1201023421), we get a palindrome (2444224442).

The spelling of 1243201021 in words is "one billion, two hundred forty-three million, two hundred one thousand, twenty-one".