1461661681 has 2 divisors, whose sum is σ = 1461661682. Its totient is φ = 1461661680.

The previous prime is 1461661673. The next prime is 1461661703. The reversal of 1461661681 is 1861661641.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1460462656 + 1199025 = 38216^2 + 1095^2 .

It is a cyclic number.

It is not a de Polignac number, because 1461661681 - 2³ = 1461661673 is a prime.

It is a super-2 number, since 2×1461661681² = 4272909739407491522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1461661381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 730830840 + 730830841.

It is an arithmetic number, because the mean of its divisors is an integer number (730830841).

Almost surely, 2^1461661681 is an apocalyptic number.

It is an amenable number.

1461661681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1461661681 is an equidigital number, since it uses as much as digits as its factorization.

1461661681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 40.

The square root of 1461661681 is about 38231.6842553398. The cubic root of 1461661681 is about 1134.8774165579.

Subtracting from 1461661681 its sum of digits (40), we obtain a palindrome (1461661641).

The spelling of 1461661681 in words is "one billion, four hundred sixty-one million, six hundred sixty-one thousand, six hundred eighty-one".