401691 has 8 divisors (see below), whose sum is σ = 538704. Its totient is φ = 266240.

The previous prime is 401689. The next prime is 401707. The reversal of 401691 is 196104.

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

It is a cyclic number.

It is not a de Polignac number, because 401691 - 2¹ = 401689 is a prime.

It is a super-2 number, since 2×401691² = 322711318962, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (401651) 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, 511 + ... + 1031.

It is an arithmetic number, because the mean of its divisors is an integer number (67338).

2⁴⁰¹⁶⁹¹ is an apocalyptic number.

401691 is a deficient number, since it is larger than the sum of its proper divisors (137013).

401691 is a wasteful number, since it uses less digits than its factorization.

401691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 781.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 401691 is about 633.7909750067. The cubic root of 401691 is about 73.7843122918.

Adding to 401691 its reverse (196104), we get a palindrome (597795).

The spelling of 401691 in words is "four hundred one thousand, six hundred ninety-one".