400649 has 4 divisors (see below), whose sum is σ = 401940. Its totient is φ = 399360.

The previous prime is 400643. The next prime is 400651. The reversal of 400649 is 946004.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 135424 + 265225 = 368^2 + 515^2 .

It is a cyclic number.

It is not a de Polignac number, because 400649 - 2¹⁶ = 335113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (400643) 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, 137 + ... + 905.

It is an arithmetic number, because the mean of its divisors is an integer number (100485).

2⁴⁰⁰⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

400649 is a deficient number, since it is larger than the sum of its proper divisors (1291).

400649 is an equidigital number, since it uses as much as digits as its factorization.

400649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1290.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 400649 is about 632.9684036348. The cubic root of 400649 is about 73.7204573813.

The spelling of 400649 in words is "four hundred thousand, six hundred forty-nine".