1681651 has 2 divisors, whose sum is σ = 1681652. Its totient is φ = 1681650.

The previous prime is 1681649. The next prime is 1681661. The reversal of 1681651 is 1561861.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1681651 - 2¹ = 1681649 is a prime.

Together with 1681649, it forms a pair of twin primes.

It is a Chen prime.

1681651 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1681621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840825 + 840826.

It is an arithmetic number, because the mean of its divisors is an integer number (840826).

2^1681651 is an apocalyptic number.

1681651 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681651 is an equidigital number, since it uses as much as digits as its factorization.

1681651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 28.

The square root of 1681651 is about 1296.7848703621. The cubic root of 1681651 is about 118.9173684292.

It can be divided in two parts, 1681 and 651, that added together give a palindrome (2332).

The spelling of 1681651 in words is "one million, six hundred eighty-one thousand, six hundred fifty-one".