51242420 has 48 divisors (see below), whose sum is σ = 117890640. Its totient is φ = 18622464.

The previous prime is 51242419. The next prime is 51242431. The reversal of 51242420 is 2424215.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 234256 + 51008164 = 484^2 + 7142^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 51242392 and 51242401.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7262 + ... + 12458.

It is an arithmetic number, because the mean of its divisors is an integer number (2456055).

Almost surely, 2^51242420 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51242420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (58945320).

51242420 is an abundant number, since it is smaller than the sum of its proper divisors (66648220).

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

51242420 is a wasteful number, since it uses less digits than its factorization.

51242420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5252 (or 5250 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 51242420 is about 7158.3811018973. The cubic root of 51242420 is about 371.4296284839.

Adding to 51242420 its reverse (2424215), we get a palindrome (53666635).

The spelling of 51242420 in words is "fifty-one million, two hundred forty-two thousand, four hundred twenty".