21155489280 has 200 divisors, whose sum is σ = 75773020752. Its totient is φ = 5641408512.

The previous prime is 21155489261. The next prime is 21155489291. The reversal of 21155489280 is 8298455112.

21155489280 is a `hidden beast` number, since 2 + 1 + 1 + 554 + 8 + 92 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 156349 + ... + 258371.

Almost surely, 2^21155489280 is an apocalyptic number.

21155489280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21155489280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37886510376).

21155489280 is an abundant number, since it is smaller than the sum of its proper divisors (54617531472).

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

21155489280 is an equidigital number, since it uses as much as digits as its factorization.

21155489280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102058 (or 102033 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 45.

The spelling of 21155489280 in words is "twenty-one billion, one hundred fifty-five million, four hundred eighty-nine thousand, two hundred eighty".