43921921 has 4 divisors (see below), whose sum is σ = 45436500. Its totient is φ = 42407344.

The previous prime is 43921919. The next prime is 43921937. The reversal of 43921921 is 12912934.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12912934 = 2 ⋅6456467.

It can be written as a sum of positive squares in 2 ways, for example, as 34680321 + 9241600 = 5889^2 + 3040^2 .

It is a cyclic number.

It is not a de Polignac number, because 43921921 - 2¹ = 43921919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43921991) 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, 757246 + ... + 757303.

It is an arithmetic number, because the mean of its divisors is an integer number (11359125).

Almost surely, 2^43921921 is an apocalyptic number.

It is an amenable number.

43921921 is a deficient number, since it is larger than the sum of its proper divisors (1514579).

43921921 is a wasteful number, since it uses less digits than its factorization.

43921921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1514578.

The product of its digits is 3888, while the sum is 31.

The square root of 43921921 is about 6627.3615413677. The cubic root of 43921921 is about 352.8258871119.

The spelling of 43921921 in words is "forty-three million, nine hundred twenty-one thousand, nine hundred twenty-one".