51388890 has 64 divisors (see below), whose sum is σ = 142331904. Its totient is φ = 11631168.

The previous prime is 51388889. The next prime is 51388891. The reversal of 51388890 is 9888315.

It is an interprime number because it is at equal distance from previous prime (51388889) and next prime (51388891).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51388891) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21327 + ... + 23613.

It is an arithmetic number, because the mean of its divisors is an integer number (2223936).

Almost surely, 2^51388890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51388890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (71165952).

51388890 is an abundant number, since it is smaller than the sum of its proper divisors (90943014).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51388890 is a wasteful number, since it uses less digits than its factorization.

51388890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2411.

The product of its (nonzero) digits is 69120, while the sum is 42.

The square root of 51388890 is about 7168.6044667006. The cubic root of 51388890 is about 371.7831867588.

It can be divided in two parts, 5138 and 8890, that added together give a triangular number (14028 = T₁₆₇).

The spelling of 51388890 in words is "fifty-one million, three hundred eighty-eight thousand, eight hundred ninety".