1661644707 has 8 divisors (see below), whose sum is σ = 2219264784. Its totient is φ = 1105893888.

The previous prime is 1661644703. The next prime is 1661644727. The reversal of 1661644707 is 7074461661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1661644707 - 2² = 1661644703 is a prime.

It is a super-2 number, since 2×1661644707² = 5522126264602231698, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (1661644703) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 465238 + ... + 468795.

It is an arithmetic number, because the mean of its divisors is an integer number (277408098).

Almost surely, 2^1661644707 is an apocalyptic number.

1661644707 is a deficient number, since it is larger than the sum of its proper divisors (557620077).

1661644707 is an equidigital number, since it uses as much as digits as its factorization.

1661644707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 934629.

The product of its (nonzero) digits is 169344, while the sum is 42.

The square root of 1661644707 is about 40763.2764507467. The cubic root of 1661644707 is about 1184.4390651078.

The spelling of 1661644707 in words is "one billion, six hundred sixty-one million, six hundred forty-four thousand, seven hundred seven".