51451921 has 2 divisors, whose sum is σ = 51451922. Its totient is φ = 51451920.

The previous prime is 51451889. The next prime is 51451927. The reversal of 51451921 is 12915415.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49547521 + 1904400 = 7039^2 + 1380^2 .

It is a cyclic number.

It is not a de Polignac number, because 51451921 - 2⁵ = 51451889 is a prime.

It is equal to p_3082933 and since 51451921 and 3082933 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51451921.

It is not a weakly prime, because it can be changed into another prime (51451927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25725960 + 25725961.

It is an arithmetic number, because the mean of its divisors is an integer number (25725961).

Almost surely, 2^51451921 is an apocalyptic number.

It is an amenable number.

51451921 is a deficient number, since it is larger than the sum of its proper divisors (1).

51451921 is an equidigital number, since it uses as much as digits as its factorization.

51451921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1800, while the sum is 28.

The square root of 51451921 is about 7172.9994423532. Note that the first 3 decimals coincide. The cubic root of 51451921 is about 371.9351281067.

The spelling of 51451921 in words is "fifty-one million, four hundred fifty-one thousand, nine hundred twenty-one".