40400809 has 2 divisors, whose sum is σ = 40400810. Its totient is φ = 40400808.

The previous prime is 40400771. The next prime is 40400813. The reversal of 40400809 is 90800404.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 40195600 + 205209 = 6340^2 + 453^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40400809 is a prime.

It is not a weakly prime, because it can be changed into another prime (40400819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20200404 + 20200405.

It is an arithmetic number, because the mean of its divisors is an integer number (20200405).

Almost surely, 2^40400809 is an apocalyptic number.

It is an amenable number.

40400809 is a deficient number, since it is larger than the sum of its proper divisors (1).

40400809 is an equidigital number, since it uses as much as digits as its factorization.

40400809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 40400809 is about 6356.1630721686. The cubic root of 40400809 is about 343.1336846828.

It can be divided in two parts, 40400 and 809, that added together give a square (41209 = 203²).

The spelling of 40400809 in words is "forty million, four hundred thousand, eight hundred nine".