51605618 has 4 divisors (see below), whose sum is σ = 77408430. Its totient is φ = 25802808.

The previous prime is 51605551. The next prime is 51605641. The reversal of 51605618 is 81650615.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81650615 = 5 ⋅16330123.

It can be written as a sum of positive squares in only one way, i.e., 32569849 + 19035769 = 5707^2 + 4363^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12901403 + ... + 12901406.

Almost surely, 2^51605618 is an apocalyptic number.

51605618 is a deficient number, since it is larger than the sum of its proper divisors (25802812).

51605618 is a wasteful number, since it uses less digits than its factorization.

51605618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25802811.

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 51605618 is about 7183.7050329200. The cubic root of 51605618 is about 372.3051077252.

The spelling of 51605618 in words is "fifty-one million, six hundred five thousand, six hundred eighteen".