406139861 has 6 divisors (see below), whose sum is σ = 417414690. Its totient is φ = 395161776.

The previous prime is 406139857. The next prime is 406139939. The reversal of 406139861 is 168931604.

It can be written as a sum of positive squares in 3 ways, for example, as 317196100 + 88943761 = 17810^2 + 9431^2 .

It is not a de Polignac number, because 406139861 - 2² = 406139857 is a prime.

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 (406139821) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 146966 + ... + 149703.

It is an arithmetic number, because the mean of its divisors is an integer number (69569115).

Almost surely, 2^406139861 is an apocalyptic number.

It is an amenable number.

406139861 is a deficient number, since it is larger than the sum of its proper divisors (11274829).

406139861 is an equidigital number, since it uses as much as digits as its factorization.

406139861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296743 (or 296706 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 38.

The square root of 406139861 is about 20152.9119732112. The cubic root of 406139861 is about 740.5570805181.

The spelling of 406139861 in words is "four hundred six million, one hundred thirty-nine thousand, eight hundred sixty-one".