51205021 has 4 divisors (see below), whose sum is σ = 58520032. Its totient is φ = 43890012.

The previous prime is 51205001. The next prime is 51205027. The reversal of 51205021 is 12050215.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12050215 = 5 ⋅2410043.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51205021 is a prime.

It is a super-2 number, since 2×51205021² = 5243908351220882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51204986 and 51205004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51205027) 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, 3657495 + ... + 3657508.

It is an arithmetic number, because the mean of its divisors is an integer number (14630008).

Almost surely, 2^51205021 is an apocalyptic number.

It is an amenable number.

51205021 is a deficient number, since it is larger than the sum of its proper divisors (7315011).

51205021 is an equidigital number, since it uses as much as digits as its factorization.

51205021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7315010.

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 51205021 is about 7155.7683724391. The cubic root of 51205021 is about 371.3392445306.

Adding to 51205021 its reverse (12050215), we get a palindrome (63255236).

The spelling of 51205021 in words is "fifty-one million, two hundred five thousand, twenty-one".