51209885 has 4 divisors (see below), whose sum is σ = 61451868. Its totient is φ = 40967904.

The previous prime is 51209869. The next prime is 51209897. The reversal of 51209885 is 58890215.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10582009 + 40627876 = 3253^2 + 6374^2 .

It is a cyclic number.

It is not a de Polignac number, because 51209885 - 2⁴ = 51209869 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5120984 + ... + 5120993.

It is an arithmetic number, because the mean of its divisors is an integer number (15362967).

Almost surely, 2^51209885 is an apocalyptic number.

It is an amenable number.

51209885 is a deficient number, since it is larger than the sum of its proper divisors (10241983).

51209885 is a wasteful number, since it uses less digits than its factorization.

51209885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10241982.

The product of its (nonzero) digits is 28800, while the sum is 38.

The square root of 51209885 is about 7156.1082300368. The cubic root of 51209885 is about 371.3510020813.

The spelling of 51209885 in words is "fifty-one million, two hundred nine thousand, eight hundred eighty-five".