15557551 has 2 divisors, whose sum is σ = 15557552. Its totient is φ = 15557550.

The previous prime is 15557527. The next prime is 15557557. The reversal of 15557551 is 15575551.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (15575551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15557551 - 2⁵ = 15557519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15557557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7778775 + 7778776.

It is an arithmetic number, because the mean of its divisors is an integer number (7778776).

Almost surely, 2^15557551 is an apocalyptic number.

15557551 is a deficient number, since it is larger than the sum of its proper divisors (1).

15557551 is an equidigital number, since it uses as much as digits as its factorization.

15557551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21875, while the sum is 34.

The square root of 15557551 is about 3944.3061493753. The cubic root of 15557551 is about 249.6397531381.

The spelling of 15557551 in words is "fifteen million, five hundred fifty-seven thousand, five hundred fifty-one".