401651681 has 2 divisors, whose sum is σ = 401651682. Its totient is φ = 401651680.

The previous prime is 401651671. The next prime is 401651743. The reversal of 401651681 is 186156104.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 401641681 + 10000 = 20041^2 + 100^2 .

It is a cyclic number.

It is not a de Polignac number, because 401651681 - 2⁶ = 401651617 is a prime.

It is a super-2 number, since 2×401651681² = 322648145700251522, which contains 22 as substring.

It is equal to p_21419537 and since 401651681 and 21419537 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (401651611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200825840 + 200825841.

It is an arithmetic number, because the mean of its divisors is an integer number (200825841).

Almost surely, 2^401651681 is an apocalyptic number.

It is an amenable number.

401651681 is a deficient number, since it is larger than the sum of its proper divisors (1).

401651681 is an equidigital number, since it uses as much as digits as its factorization.

401651681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 401651681 is about 20041.2494869956. The cubic root of 401651681 is about 737.8190478621.

The spelling of 401651681 in words is "four hundred one million, six hundred fifty-one thousand, six hundred eighty-one".