51391198 has 4 divisors (see below), whose sum is σ = 77086800. Its totient is φ = 25695598.

The previous prime is 51391139. The next prime is 51391199. The reversal of 51391198 is 89119315.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51391199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12847798 + ... + 12847801.

It is an arithmetic number, because the mean of its divisors is an integer number (19271700).

Almost surely, 2^51391198 is an apocalyptic number.

51391198 is a deficient number, since it is larger than the sum of its proper divisors (25695602).

51391198 is a wasteful number, since it uses less digits than its factorization.

51391198 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25695601.

The product of its digits is 9720, while the sum is 37.

The square root of 51391198 is about 7168.7654446215. The cubic root of 51391198 is about 371.7887525711.

The spelling of 51391198 in words is "fifty-one million, three hundred ninety-one thousand, one hundred ninety-eight".