51020981 has 6 divisors (see below), whose sum is σ = 56081046. Its totient is φ = 46382600.

The previous prime is 51020929. The next prime is 51020993. The reversal of 51020981 is 18902015.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 40844881 + 10176100 = 6391^2 + 3190^2 .

It is not a de Polignac number, because 51020981 - 2¹⁸ = 50758837 is a prime.

It is a super-2 number, since 2×51020981² = 5206281004404722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51020981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51025981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 210710 + ... + 210951.

It is an arithmetic number, because the mean of its divisors is an integer number (9346841).

Almost surely, 2^51020981 is an apocalyptic number.

It is an amenable number.

51020981 is a deficient number, since it is larger than the sum of its proper divisors (5060065).

51020981 is a wasteful number, since it uses less digits than its factorization.

51020981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421683 (or 421672 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 51020981 is about 7142.8972413160. The cubic root of 51020981 is about 370.8938239186.

Adding to 51020981 its reverse (18902015), we get a palindrome (69922996).

The spelling of 51020981 in words is "fifty-one million, twenty thousand, nine hundred eighty-one".