400709 has 4 divisors (see below), whose sum is σ = 407340. Its totient is φ = 394080.

The previous prime is 400703. The next prime is 400711. The reversal of 400709 is 907004.

400709 = T₁₂ + T₁₃ + ... + T₁₃₃.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 172225 + 228484 = 415^2 + 478^2 .

It is a cyclic number.

It is not a de Polignac number, because 400709 - 2¹⁶ = 335173 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400703) 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, 3224 + ... + 3345.

It is an arithmetic number, because the mean of its divisors is an integer number (101835).

2⁴⁰⁰⁷⁰⁹ is an apocalyptic number.

It is an amenable number.

400709 is a deficient number, since it is larger than the sum of its proper divisors (6631).

400709 is an equidigital number, since it uses as much as digits as its factorization.

400709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6630.

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 400709 is about 633.0157975912. The cubic root of 400709 is about 73.7241372496.

Subtracting from 400709 its sum of digits (20), we obtain a square (400689 = 633²).

The spelling of 400709 in words is "four hundred thousand, seven hundred nine".