1661670687 has 4 divisors (see below), whose sum is σ = 2215560920. Its totient is φ = 1107780456.

The previous prime is 1661670677. The next prime is 1661670697. The reversal of 1661670687 is 7860761661.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1661670677) and next prime (1661670697).

It is not a de Polignac number, because 1661670687 - 2¹⁰ = 1661669663 is a prime.

It is a super-2 number, since 2×1661670687² = 5522298944070103938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661670607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 276945112 + ... + 276945117.

It is an arithmetic number, because the mean of its divisors is an integer number (553890230).

Almost surely, 2^1661670687 is an apocalyptic number.

1661670687 is a deficient number, since it is larger than the sum of its proper divisors (553890233).

1661670687 is an equidigital number, since it uses as much as digits as its factorization.

1661670687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 553890232.

The product of its (nonzero) digits is 508032, while the sum is 48.

The square root of 1661670687 is about 40763.5951186840. The cubic root of 1661670687 is about 1184.4452380212.

The spelling of 1661670687 in words is "one billion, six hundred sixty-one million, six hundred seventy thousand, six hundred eighty-seven".