51251223421 has 2 divisors, whose sum is σ = 51251223422. Its totient is φ = 51251223420.

The previous prime is 51251223383. The next prime is 51251223473. The reversal of 51251223421 is 12432215215.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42076265625 + 9174957796 = 205125^2 + 95786^2 .

It is a cyclic number.

It is not a de Polignac number, because 51251223421 - 2⁹ = 51251222909 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51251223421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51251223521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25625611710 + 25625611711.

It is an arithmetic number, because the mean of its divisors is an integer number (25625611711).

Almost surely, 2^51251223421 is an apocalyptic number.

It is an amenable number.

51251223421 is a deficient number, since it is larger than the sum of its proper divisors (1).

51251223421 is an equidigital number, since it uses as much as digits as its factorization.

51251223421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4800, while the sum is 28.

Adding to 51251223421 its reverse (12432215215), we get a palindrome (63683438636).

The spelling of 51251223421 in words is "fifty-one billion, two hundred fifty-one million, two hundred twenty-three thousand, four hundred twenty-one".