51521021 has 2 divisors, whose sum is σ = 51521022. Its totient is φ = 51521020.

The previous prime is 51521017. The next prime is 51521077. The reversal of 51521021 is 12012515.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50608996 + 912025 = 7114^2 + 955^2 .

It is a cyclic number.

It is not a de Polignac number, because 51521021 - 2² = 51521017 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51524021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25760510 + 25760511.

It is an arithmetic number, because the mean of its divisors is an integer number (25760511).

Almost surely, 2^51521021 is an apocalyptic number.

It is an amenable number.

51521021 is a deficient number, since it is larger than the sum of its proper divisors (1).

51521021 is an equidigital number, since it uses as much as digits as its factorization.

51521021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 51521021 is about 7177.8145002501. The cubic root of 51521021 is about 372.1015567522.

Adding to 51521021 its reverse (12012515), we get a palindrome (63533536).

The spelling of 51521021 in words is "fifty-one million, five hundred twenty-one thousand, twenty-one".