400538661 has 16 divisors (see below), whose sum is σ = 541404864. Its totient is φ = 263360384.

The previous prime is 400538641. The next prime is 400538687. The reversal of 400538661 is 166835004.

It is a cyclic number.

It is not a de Polignac number, because 400538661 - 2⁶ = 400538597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400538641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 212455 + ... + 214331.

It is an arithmetic number, because the mean of its divisors is an integer number (33837804).

Almost surely, 2^400538661 is an apocalyptic number.

It is an amenable number.

400538661 is a deficient number, since it is larger than the sum of its proper divisors (140866203).

400538661 is a wasteful number, since it uses less digits than its factorization.

400538661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2820.

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 400538661 is about 20013.4619943677. The cubic root of 400538661 is about 737.1368920566.

The spelling of 400538661 in words is "four hundred million, five hundred thirty-eight thousand, six hundred sixty-one".