401431661 has 2 divisors, whose sum is σ = 401431662. Its totient is φ = 401431660.

The previous prime is 401431621. The next prime is 401431663. The reversal of 401431661 is 166134104.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 331458436 + 69973225 = 18206^2 + 8365^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-401431661 is a prime.

It is a super-2 number, since 2×401431661² = 322294756906437842, which contains 22 as substring.

Together with 401431663, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 401431661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (401431663) 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 as a sum of consecutive naturals, namely, 200715830 + 200715831.

It is an arithmetic number, because the mean of its divisors is an integer number (200715831).

Almost surely, 2^401431661 is an apocalyptic number.

It is an amenable number.

401431661 is a deficient number, since it is larger than the sum of its proper divisors (1).

401431661 is an equidigital number, since it uses as much as digits as its factorization.

401431661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 401431661 is about 20035.7595563532. The cubic root of 401431661 is about 737.6843004302.

Adding to 401431661 its reverse (166134104), we get a palindrome (567565765).

The spelling of 401431661 in words is "four hundred one million, four hundred thirty-one thousand, six hundred sixty-one".