51213540 has 48 divisors (see below), whose sum is σ = 163884672. Its totient is φ = 11705856.

The previous prime is 51213523. The next prime is 51213583. The reversal of 51213540 is 4531215.

51213540 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60549 + ... + 61388.

It is an arithmetic number, because the mean of its divisors is an integer number (3414264).

Almost surely, 2^51213540 is an apocalyptic number.

It is an amenable number.

51213540 is an abundant number, since it is smaller than the sum of its proper divisors (112671132).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51213540 is a wasteful number, since it uses less digits than its factorization.

51213540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121956 (or 121954 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 51213540 is about 7156.3636017184. The cubic root of 51213540 is about 371.3598366753.

Adding to 51213540 its reverse (4531215), we get a palindrome (55744755).

The spelling of 51213540 in words is "fifty-one million, two hundred thirteen thousand, five hundred forty".