51555551 has 4 divisors (see below), whose sum is σ = 52066104. Its totient is φ = 51045000.

The previous prime is 51555521. The next prime is 51555571. The reversal of 51555551 is 15555515.

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 51555551 - 2⁶ = 51555487 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 (51555521) 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, 255125 + ... + 255326.

It is an arithmetic number, because the mean of its divisors is an integer number (13016526).

Almost surely, 2^51555551 is an apocalyptic number.

51555551 is a deficient number, since it is larger than the sum of its proper divisors (510553).

51555551 is a wasteful number, since it uses less digits than its factorization.

51555551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510552.

The product of its digits is 15625, while the sum is 32.

The square root of 51555551 is about 7180.2194256165. The cubic root of 51555551 is about 372.1846671482.

The spelling of 51555551 in words is "fifty-one million, five hundred fifty-five thousand, five hundred fifty-one".