21424804621520 has 20 divisors (see below), whose sum is σ = 49812670745220. Its totient is φ = 8569921848576.

The previous prime is 21424804621513. The next prime is 21424804621559. The reversal of 21424804621520 is 2512640842412.

It can be written as a sum of positive squares in 2 ways, for example, as 3185311145536 + 18239493475984 = 1784744^2 + 4270772^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×21424804621520² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133905028805 + ... + 133905028964.

It is an arithmetic number, because the mean of its divisors is an integer number (2490633537261).

Almost surely, 2^{21424804621520} is an apocalyptic number.

21424804621520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21424804621520 is an abundant number, since it is smaller than the sum of its proper divisors (28387866123700).

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

21424804621520 is a wasteful number, since it uses less digits than its factorization.

21424804621520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267810057782 (or 267810057776 counting only the distinct ones).

The product of its (nonzero) digits is 245760, while the sum is 41.

The spelling of 21424804621520 in words is "twenty-one trillion, four hundred twenty-four billion, eight hundred four million, six hundred twenty-one thousand, five hundred twenty".