15551591 has 4 divisors (see below), whose sum is σ = 16965384. Its totient is φ = 14137800.

The previous prime is 15551579. The next prime is 15551597. The reversal of 15551591 is 19515551.

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

It is a cyclic number.

It is not a de Polignac number, because 15551591 - 2¹⁴ = 15535207 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 (15551597) 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, 706880 + ... + 706901.

It is an arithmetic number, because the mean of its divisors is an integer number (4241346).

Almost surely, 2^15551591 is an apocalyptic number.

15551591 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

15551591 is a deficient number, since it is larger than the sum of its proper divisors (1413793).

15551591 is a wasteful number, since it uses less digits than its factorization.

15551591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1413792.

The product of its digits is 5625, while the sum is 32.

The square root of 15551591 is about 3943.5505575560. The cubic root of 15551591 is about 249.6078705930.

The spelling of 15551591 in words is "fifteen million, five hundred fifty-one thousand, five hundred ninety-one".