21583315278 has 288 divisors, whose sum is σ = 59498150400. Its totient is φ = 5618688768.

The previous prime is 21583315267. The next prime is 21583315283. The reversal of 21583315278 is 87251338512.

21583315278 is a `hidden beast` number, since 2 + 15 + 83 + 31 + 527 + 8 = 666.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 52770738 + ... + 52771146.

It is an arithmetic number, because the mean of its divisors is an integer number (206590800).

Almost surely, 2^21583315278 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21583315278, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29749075200).

21583315278 is an abundant number, since it is smaller than the sum of its proper divisors (37914835122).

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

21583315278 is a wasteful number, since it uses less digits than its factorization.

21583315278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 564 (or 554 counting only the distinct ones).

The product of its digits is 403200, while the sum is 45.

The spelling of 21583315278 in words is "twenty-one billion, five hundred eighty-three million, three hundred fifteen thousand, two hundred seventy-eight".