51123421 has 4 divisors (see below), whose sum is σ = 51155932. Its totient is φ = 51090912.

The previous prime is 51123409. The next prime is 51123427. The reversal of 51123421 is 12432115.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12432115 = 5 ⋅2486423.

It can be written as a sum of positive squares in 2 ways, for example, as 10304100 + 40819321 = 3210^2 + 6389^2 .

It is a cyclic number.

It is not a de Polignac number, because 51123421 - 2⁵ = 51123389 is a prime.

It is a super-2 number, since 2×51123421² = 5227208349486482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51123427) 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, 13770 + ... + 17083.

It is an arithmetic number, because the mean of its divisors is an integer number (12788983).

Almost surely, 2^51123421 is an apocalyptic number.

It is an amenable number.

51123421 is a deficient number, since it is larger than the sum of its proper divisors (32511).

51123421 is a wasteful number, since it uses less digits than its factorization.

51123421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32510.

The product of its digits is 240, while the sum is 19.

The square root of 51123421 is about 7150.0644053043. The cubic root of 51123421 is about 371.1418850268.

Adding to 51123421 its reverse (12432115), we get a palindrome (63555536).

It can be divided in two parts, 511 and 23421, that added together give a palindrome (23932).

The spelling of 51123421 in words is "fifty-one million, one hundred twenty-three thousand, four hundred twenty-one".