51521240 has 32 divisors (see below), whose sum is σ = 116208000. Its totient is φ = 20557824.

The previous prime is 51521209. The next prime is 51521263. The reversal of 51521240 is 4212515.

It is a super-2 number, since 2×51521240² = 5308876342275200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 17816 + ... + 20504.

It is an arithmetic number, because the mean of its divisors is an integer number (3631500).

Almost surely, 2^51521240 is an apocalyptic number.

It is an amenable number.

51521240 is an abundant number, since it is smaller than the sum of its proper divisors (64686760).

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

51521240 is a wasteful number, since it uses less digits than its factorization.

51521240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3179 (or 3175 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 51521240 is about 7177.8297555738. The cubic root of 51521240 is about 372.1020839812.

Adding to 51521240 its reverse (4212515), we get a palindrome (55733755).

The spelling of 51521240 in words is "fifty-one million, five hundred twenty-one thousand, two hundred forty".