400344781 has 4 divisors (see below), whose sum is σ = 423894492. Its totient is φ = 376795072.

The previous prime is 400344761. The next prime is 400344793. The reversal of 400344781 is 187443004.

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 148011556 + 252333225 = 12166^2 + 15885^2 .

It is not a de Polignac number, because 400344781 - 2⁷ = 400344653 is a prime.

It is a super-2 number, since 2×400344781² = 320551887347875922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400344751) 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, 11774830 + ... + 11774863.

It is an arithmetic number, because the mean of its divisors is an integer number (105973623).

Almost surely, 2^400344781 is an apocalyptic number.

It is an amenable number.

400344781 is a deficient number, since it is larger than the sum of its proper divisors (23549711).

400344781 is a wasteful number, since it uses less digits than its factorization.

400344781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23549710.

The product of its (nonzero) digits is 10752, while the sum is 31.

The square root of 400344781 is about 20008.6176683948. The cubic root of 400344781 is about 737.0179362769.

Adding to 400344781 its reverse (187443004), we get a palindrome (587787785).

It can be divided in two parts, 4003 and 44781, that added together give a palindrome (48784).

The spelling of 400344781 in words is "four hundred million, three hundred forty-four thousand, seven hundred eighty-one".