15978551 has 2 divisors, whose sum is σ = 15978552. Its totient is φ = 15978550.

The previous prime is 15978533. The next prime is 15978553. The reversal of 15978551 is 15587951.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 15978551 - 2¹⁰ = 15977527 is a prime.

Together with 15978553, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 15978499 and 15978508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15978553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7989275 + 7989276.

It is an arithmetic number, because the mean of its divisors is an integer number (7989276).

Almost surely, 2^15978551 is an apocalyptic number.

15978551 is a deficient number, since it is larger than the sum of its proper divisors (1).

15978551 is an equidigital number, since it uses as much as digits as its factorization.

15978551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63000, while the sum is 41.

The square root of 15978551 is about 3997.3179758433. The cubic root of 15978551 is about 251.8715594314.

The spelling of 15978551 in words is "fifteen million, nine hundred seventy-eight thousand, five hundred fifty-one".