1661634505 has 16 divisors (see below), whose sum is σ = 2028412800. Its totient is φ = 1306432512.

The previous prime is 1661634497. The next prime is 1661634529. The reversal of 1661634505 is 5054361661.

It is a cyclic number.

It is not a de Polignac number, because 1661634505 - 2³ = 1661634497 is a prime.

It is a super-2 number, since 2×1661634505² = 5522058456413190050, which contains 22 as substring.

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, 144892 + ... + 155938.

It is an arithmetic number, because the mean of its divisors is an integer number (126775800).

Almost surely, 2^1661634505 is an apocalyptic number.

It is an amenable number.

1661634505 is a deficient number, since it is larger than the sum of its proper divisors (366778295).

1661634505 is a wasteful number, since it uses less digits than its factorization.

1661634505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11568.

The product of its (nonzero) digits is 64800, while the sum is 37.

The square root of 1661634505 is about 40763.1513134105. The cubic root of 1661634505 is about 1184.4366410693.

The spelling of 1661634505 in words is "one billion, six hundred sixty-one million, six hundred thirty-four thousand, five hundred five".