21261667553280 has 4160 divisors, whose sum is σ = 100474868736000. Its totient is φ = 4260640849920.

The previous prime is 21261667553261. The next prime is 21261667553317. The reversal of 21261667553280 is 8235576616212.

21261667553280 is a `hidden beast` number, since 2 + 1 + 2 + 6 + 1 + 6 + 6 + 7 + 553 + 2 + 80 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 269135032281 + ... + 269135032359.

Almost surely, 2^{21261667553280} is an apocalyptic number.

21261667553280 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 21261667553280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50237434368000).

21261667553280 is an abundant number, since it is smaller than the sum of its proper divisors (79213201182720).

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

21261667553280 is an equidigital number, since it uses as much as digits as its factorization.

21261667553280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195 (or 150 counting only the distinct ones).

The product of its (nonzero) digits is 7257600, while the sum is 54.

The spelling of 21261667553280 in words is "twenty-one trillion, two hundred sixty-one billion, six hundred sixty-seven million, five hundred fifty-three thousand, two hundred eighty".