51221881380 has 96 divisors (see below), whose sum is σ = 147136848768. Its totient is φ = 13306291200.

The previous prime is 51221881363. The next prime is 51221881387. The reversal of 51221881380 is 8318812215.

It is a super-2 number, since 2×51221881380² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51221881387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1684794 + ... + 1714926.

It is an arithmetic number, because the mean of its divisors is an integer number (1532675508).

Almost surely, 2^51221881380 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51221881380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (73568424384).

51221881380 is an abundant number, since it is smaller than the sum of its proper divisors (95914967388).

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

51221881380 is a wasteful number, since it uses less digits than its factorization.

51221881380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30877 (or 30875 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 39.

The spelling of 51221881380 in words is "fifty-one billion, two hundred twenty-one million, eight hundred eighty-one thousand, three hundred eighty".