1661651005 has 12 divisors (see below), whose sum is σ = 2319529500. Its totient is φ = 1139417664.

The previous prime is 1661650997. The next prime is 1661651051. The reversal of 1661651005 is 5001561661.

It can be written as a sum of positive squares in 2 ways, for example, as 166978084 + 1494672921 = 12922^2 + 38661^2 .

It is not a de Polignac number, because 1661651005 - 2³ = 1661650997 is a prime.

It is a super-2 number, since 2×1661651005² = 5522168124835020050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3390880 + ... + 3391369.

It is an arithmetic number, because the mean of its divisors is an integer number (193294125).

Almost surely, 2^1661651005 is an apocalyptic number.

It is an amenable number.

1661651005 is a deficient number, since it is larger than the sum of its proper divisors (657878495).

1661651005 is an equidigital number, since it uses as much as digits as its factorization.

1661651005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6782268 (or 6782261 counting only the distinct ones).

The product of its (nonzero) digits is 5400, while the sum is 31.

The square root of 1661651005 is about 40763.3537015786. The cubic root of 1661651005 is about 1184.4405615344.

The spelling of 1661651005 in words is "one billion, six hundred sixty-one million, six hundred fifty-one thousand, five".