1651661565 has 16 divisors (see below), whose sum is σ = 2643281088. Its totient is φ = 880678656.

The previous prime is 1651661551. The next prime is 1651661581. The reversal of 1651661565 is 5651661561.

It is not a de Polignac number, because 1651661565 - 2⁴ = 1651661549 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69909 + ... + 90501.

It is an arithmetic number, because the mean of its divisors is an integer number (165205068).

Almost surely, 2^1651661565 is an apocalyptic number.

1651661565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1651661565 is a deficient number, since it is larger than the sum of its proper divisors (991619523).

1651661565 is a wasteful number, since it uses less digits than its factorization.

1651661565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25948.

The product of its digits is 162000, while the sum is 42.

The square root of 1651661565 is about 40640.6393281405. The cubic root of 1651661565 is about 1182.0622667831.

The spelling of 1651661565 in words is "one billion, six hundred fifty-one million, six hundred sixty-one thousand, five hundred sixty-five".