40400021 has 2 divisors, whose sum is σ = 40400022. Its totient is φ = 40400020.

The previous prime is 40400011. The next prime is 40400027. The reversal of 40400021 is 12000404.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26635921 + 13764100 = 5161^2 + 3710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40400021 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 40399975 and 40400011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40400027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20200010 + 20200011.

It is an arithmetic number, because the mean of its divisors is an integer number (20200011).

Almost surely, 2^40400021 is an apocalyptic number.

It is an amenable number.

40400021 is a deficient number, since it is larger than the sum of its proper divisors (1).

40400021 is an equidigital number, since it uses as much as digits as its factorization.

40400021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 40400021 is about 6356.1010847846. The cubic root of 40400021 is about 343.1314537778.

Adding to 40400021 its reverse (12000404), we get a palindrome (52400425).

The spelling of 40400021 in words is "forty million, four hundred thousand, twenty-one".