1611781609 has 9 divisors (see below), whose sum is σ = 1701882423. Its totient is φ = 1526228352.

The previous prime is 1611781607. The next prime is 1611781631. The reversal of 1611781609 is 9061871161.

The square root of 1611781609 is 40147.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1525225 + 1610256384 = 1235^2 + 40128^2 .

It is not a de Polignac number, because 1611781609 - 2¹ = 1611781607 is a prime.

It is a super-2 number, since 2×1611781609² = 5195679910221257762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1611781601) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 761737 + ... + 763849.

It is an arithmetic number, because the mean of its divisors is an integer number (189098047).

Almost surely, 2^1611781609 is an apocalyptic number.

1611781609 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

1611781609 is the 40147-th square number.

1611781609 is the 20074-th centered octagonal number.

It is an amenable number.

1611781609 is a deficient number, since it is larger than the sum of its proper divisors (90100814).

1611781609 is an frugal number, since it uses more digits than its factorization.

1611781609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4264 (or 2132 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 40.

The cubic root of 1611781609 is about 1172.4708803875.

The spelling of 1611781609 in words is "one billion, six hundred eleven million, seven hundred eighty-one thousand, six hundred nine".