43819921 has 2 divisors, whose sum is σ = 43819922. Its totient is φ = 43819920.

The previous prime is 43819913. The next prime is 43819969. The reversal of 43819921 is 12991834.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 36180225 + 7639696 = 6015^2 + 2764^2 .

It is a cyclic number.

It is not a de Polignac number, because 43819921 - 2³ = 43819913 is a prime.

It is not a weakly prime, because it can be changed into another prime (43819901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21909960 + 21909961.

It is an arithmetic number, because the mean of its divisors is an integer number (21909961).

Almost surely, 2^43819921 is an apocalyptic number.

It is an amenable number.

43819921 is a deficient number, since it is larger than the sum of its proper divisors (1).

43819921 is an equidigital number, since it uses as much as digits as its factorization.

43819921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 37.

The square root of 43819921 is about 6619.6616983045. The cubic root of 43819921 is about 352.5525525658.

The spelling of 43819921 in words is "forty-three million, eight hundred nineteen thousand, nine hundred twenty-one".