75440821 has 4 divisors (see below), whose sum is σ = 75524544. Its totient is φ = 75357100.

The previous prime is 75440819. The next prime is 75440843. The reversal of 75440821 is 12804457.

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 3-Lehmer number, since φ(75440821) divides (75440821-1)³.

It is a cyclic number.

It is not a de Polignac number, because 75440821 - 2¹ = 75440819 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (75440021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40495 + ... + 42316.

It is an arithmetic number, because the mean of its divisors is an integer number (18881136).

Almost surely, 2^75440821 is an apocalyptic number.

It is an amenable number.

75440821 is a deficient number, since it is larger than the sum of its proper divisors (83723).

75440821 is an equidigital number, since it uses as much as digits as its factorization.

75440821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83722.

The product of its (nonzero) digits is 8960, while the sum is 31.

The square root of 75440821 is about 8685.6675621394. The cubic root of 75440821 is about 422.5409476787.

It can be divided in two parts, 75 and 440821, that added together give a square (440896 = 664²).

The spelling of 75440821 in words is "seventy-five million, four hundred forty thousand, eight hundred twenty-one".