1244620021 has 4 divisors (see below), whose sum is σ = 1244965312. Its totient is φ = 1244274732.

The previous prime is 1244619991. The next prime is 1244620033. The reversal of 1244620021 is 1200264421.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1244620021 - 2²⁵ = 1211065589 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1244619974 and 1244620001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1244620121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 167181 + ... + 174466.

It is an arithmetic number, because the mean of its divisors is an integer number (311241328).

Almost surely, 2^1244620021 is an apocalyptic number.

It is an amenable number.

1244620021 is a deficient number, since it is larger than the sum of its proper divisors (345291).

1244620021 is an equidigital number, since it uses as much as digits as its factorization.

1244620021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345290.

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 1244620021 is about 35279.1726235183. The cubic root of 1244620021 is about 1075.6696807288.

Adding to 1244620021 its reverse (1200264421), we get a palindrome (2444884442).

Subtracting from 1244620021 its reverse (1200264421), we obtain a square (44355600 = 6660²).

The spelling of 1244620021 in words is "one billion, two hundred forty-four million, six hundred twenty thousand, twenty-one".