405739681 has 8 divisors (see below), whose sum is σ = 408508520. Its totient is φ = 402979968.

The previous prime is 405739657. The next prime is 405739703. The reversal of 405739681 is 186937504.

It can be written as a sum of positive squares in 4 ways, for example, as 179989056 + 225750625 = 13416^2 + 15025^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 3-Lehmer number, since φ(405739681) divides (405739681-1)³.

It is a cyclic number.

It is a Carmichael number.

It is a de Polignac number, because none of the positive numbers 2^k-405739681 is a prime.

It is a super-2 number, since 2×405739681² = 329249377475963522, which contains 22 as substring.

It is a deceptive number, since it divides R_405739680.

It is not an unprimeable number, because it can be changed into a prime (405739381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 102715 + ... + 106591.

It is an arithmetic number, because the mean of its divisors is an integer number (51063565).

It is a Poulet number, since it divides 2^405739680-1.

Almost surely, 2^405739681 is an apocalyptic number.

It is an amenable number.

405739681 is a deficient number, since it is larger than the sum of its proper divisors (2768839).

405739681 is a wasteful number, since it uses less digits than its factorization.

405739681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4563.

The product of its (nonzero) digits is 181440, while the sum is 43.

The square root of 405739681 is about 20142.9809362964. The cubic root of 405739681 is about 740.3137706389.

The spelling of 405739681 in words is "four hundred five million, seven hundred thirty-nine thousand, six hundred eighty-one".