51504210021 has 32 divisors (see below), whose sum is σ = 80213328000. Its totient is φ = 29048391680.

The previous prime is 51504210019. The next prime is 51504210029. The reversal of 51504210021 is 12001240515.

It is not a de Polignac number, because 51504210021 - 2¹ = 51504210019 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51504210021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51504210029) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 465846 + ... + 565703.

It is an arithmetic number, because the mean of its divisors is an integer number (2506666500).

Almost surely, 2^51504210021 is an apocalyptic number.

51504210021 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

51504210021 is a deficient number, since it is larger than the sum of its proper divisors (28709117979).

51504210021 is a wasteful number, since it uses less digits than its factorization.

51504210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1031669.

The product of its (nonzero) digits is 400, while the sum is 21.

Adding to 51504210021 its reverse (12001240515), we get a palindrome (63505450536).

The spelling of 51504210021 in words is "fifty-one billion, five hundred four million, two hundred ten thousand, twenty-one".