1608616781 has 2 divisors, whose sum is σ = 1608616782. Its totient is φ = 1608616780.

The previous prime is 1608616759. The next prime is 1608616813. The reversal of 1608616781 is 1876168061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1435273225 + 173343556 = 37885^2 + 13166^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1608616781 is a prime.

It is a super-2 number, since 2×1608616781² = 5175295896229603922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1608616081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 804308390 + 804308391.

It is an arithmetic number, because the mean of its divisors is an integer number (804308391).

Almost surely, 2^1608616781 is an apocalyptic number.

It is an amenable number.

1608616781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1608616781 is an equidigital number, since it uses as much as digits as its factorization.

1608616781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96768, while the sum is 44.

The square root of 1608616781 is about 40107.5651342736. The cubic root of 1608616781 is about 1171.7029723763.

The spelling of 1608616781 in words is "one billion, six hundred eight million, six hundred sixteen thousand, seven hundred eighty-one".