15687661 has 4 divisors (see below), whose sum is σ = 17113824. Its totient is φ = 14261500.

The previous prime is 15687649. The next prime is 15687691. The reversal of 15687661 is 16678651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 15687661 - 2¹¹ = 15685613 is a prime.

It is a super-2 number, since 2×15687661² = 492205415301842, 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 (15687601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 713065 + ... + 713086.

It is an arithmetic number, because the mean of its divisors is an integer number (4278456).

Almost surely, 2^15687661 is an apocalyptic number.

15687661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

15687661 is a deficient number, since it is larger than the sum of its proper divisors (1426163).

15687661 is a wasteful number, since it uses less digits than its factorization.

15687661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1426162.

The product of its digits is 60480, while the sum is 40.

The square root of 15687661 is about 3960.7652038463. The cubic root of 15687661 is about 250.3337462555. Note that the first 3 decimals are identical.

It can be divided in two parts, 1568 and 7661, that added together give a palindrome (9229).

The spelling of 15687661 in words is "fifteen million, six hundred eighty-seven thousand, six hundred sixty-one".