400078981 has 2 divisors, whose sum is σ = 400078982. Its totient is φ = 400078980.

The previous prime is 400078979. The next prime is 400079011. The reversal of 400078981 is 189870004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 398002500 + 2076481 = 19950^2 + 1441^2 .

It is a cyclic number.

It is not a de Polignac number, because 400078981 - 2¹ = 400078979 is a prime.

It is a super-2 number, since 2×400078981² = 320126382075996722, which contains 22 as substring.

Together with 400078979, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 400078981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400078181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200039490 + 200039491.

It is an arithmetic number, because the mean of its divisors is an integer number (200039491).

Almost surely, 2^400078981 is an apocalyptic number.

It is an amenable number.

400078981 is a deficient number, since it is larger than the sum of its proper divisors (1).

400078981 is an equidigital number, since it uses as much as digits as its factorization.

400078981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 400078981 is about 20001.9744275409. The cubic root of 400078981 is about 736.8547912853.

The spelling of 400078981 in words is "four hundred million, seventy-eight thousand, nine hundred eighty-one".