15661543 has 2 divisors, whose sum is σ = 15661544. Its totient is φ = 15661542.

The previous prime is 15661507. The next prime is 15661571. The reversal of 15661543 is 34516651.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 15661543 - 2⁹ = 15661031 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15661343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7830771 + 7830772.

It is an arithmetic number, because the mean of its divisors is an integer number (7830772).

Almost surely, 2^15661543 is an apocalyptic number.

15661543 is a deficient number, since it is larger than the sum of its proper divisors (1).

15661543 is an equidigital number, since it uses as much as digits as its factorization.

15661543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10800, while the sum is 31.

The square root of 15661543 is about 3957.4667402266. The cubic root of 15661543 is about 250.1947442593.

The spelling of 15661543 in words is "fifteen million, six hundred sixty-one thousand, five hundred forty-three".