15551661 has 8 divisors (see below), whose sum is σ = 20937280. Its totient is φ = 10266912.

The previous prime is 15551659. The next prime is 15551663. The reversal of 15551661 is 16615551.

It is an interprime number because it is at equal distance from previous prime (15551659) and next prime (15551663).

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

It is not a de Polignac number, because 15551661 - 2¹ = 15551659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15551663) 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, 24856 + ... + 25473.

It is an arithmetic number, because the mean of its divisors is an integer number (2617160).

Almost surely, 2^15551661 is an apocalyptic number.

It is an amenable number.

15551661 is a deficient number, since it is larger than the sum of its proper divisors (5385619).

15551661 is a wasteful number, since it uses less digits than its factorization.

15551661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50435.

The product of its digits is 4500, while the sum is 30.

The square root of 15551661 is about 3943.5594327967. The cubic root of 15551661 is about 249.6082450997.

The spelling of 15551661 in words is "fifteen million, five hundred fifty-one thousand, six hundred sixty-one".