51220421 has 4 divisors (see below), whose sum is σ = 58537632. Its totient is φ = 43903212.

The previous prime is 51220417. The next prime is 51220423. The reversal of 51220421 is 12402215.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51220421 - 2² = 51220417 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51220421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51220423) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3658595 + ... + 3658608.

It is an arithmetic number, because the mean of its divisors is an integer number (14634408).

Almost surely, 2^51220421 is an apocalyptic number.

It is an amenable number.

51220421 is a deficient number, since it is larger than the sum of its proper divisors (7317211).

51220421 is an equidigital number, since it uses as much as digits as its factorization.

51220421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7317210.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 51220421 is about 7156.8443464980. The cubic root of 51220421 is about 371.3764677758.

Adding to 51220421 its reverse (12402215), we get a palindrome (63622636).

The spelling of 51220421 in words is "fifty-one million, two hundred twenty thousand, four hundred twenty-one".