1243440921 has 16 divisors (see below), whose sum is σ = 1749608000. Its totient is φ = 783338688.

The previous prime is 1243440899. The next prime is 1243440929. The reversal of 1243440921 is 1290443421.

It is not a de Polignac number, because 1243440921 - 2¹⁷ = 1243309849 is a prime.

It is a super-2 number, since 2×1243440921² = 3092290648034656482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1243440929) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4846 + ... + 50103.

It is an arithmetic number, because the mean of its divisors is an integer number (109350500).

Almost surely, 2^1243440921 is an apocalyptic number.

It is an amenable number.

1243440921 is a deficient number, since it is larger than the sum of its proper divisors (506167079).

1243440921 is a wasteful number, since it uses less digits than its factorization.

1243440921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55368.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 1243440921 is about 35262.4576710132. The cubic root of 1243440921 is about 1075.3298921914.

The spelling of 1243440921 in words is "one billion, two hundred forty-three million, four hundred forty thousand, nine hundred twenty-one".