1901681 has 2 divisors, whose sum is σ = 1901682. Its totient is φ = 1901680.

The previous prime is 1901651. The next prime is 1901699. The reversal of 1901681 is 1861091.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1018081 + 883600 = 1009^2 + 940^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1901681 is a prime.

It is a super-2 number, since 2×1901681² = 7232781251522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1901681.

It is not a weakly prime, because it can be changed into another prime (1901651) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 950840 + 950841.

It is an arithmetic number, because the mean of its divisors is an integer number (950841).

2^1901681 is an apocalyptic number.

It is an amenable number.

1901681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1901681 is an equidigital number, since it uses as much as digits as its factorization.

1901681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 26.

The square root of 1901681 is about 1379.0145031870. The cubic root of 1901681 is about 123.8927489203.

The spelling of 1901681 in words is "one million, nine hundred one thousand, six hundred eighty-one".