1681451881 has 2 divisors, whose sum is σ = 1681451882. Its totient is φ = 1681451880.

The previous prime is 1681451819. The next prime is 1681451887. The reversal of 1681451881 is 1881541861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1585313856 + 96138025 = 39816^2 + 9805^2 .

It is a cyclic number.

It is not a de Polignac number, because 1681451881 - 2⁷ = 1681451753 is a prime.

It is a super-2 number, since 2×1681451881² = 5654560856236876322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1681451887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840725940 + 840725941.

It is an arithmetic number, because the mean of its divisors is an integer number (840725941).

Almost surely, 2^1681451881 is an apocalyptic number.

It is an amenable number.

1681451881 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681451881 is an equidigital number, since it uses as much as digits as its factorization.

1681451881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 61440, while the sum is 43.

The square root of 1681451881 is about 41005.5103736071. The cubic root of 1681451881 is about 1189.1267470019.

The spelling of 1681451881 in words is "one billion, six hundred eighty-one million, four hundred fifty-one thousand, eight hundred eighty-one".