21266166465220 has 24 divisors (see below), whose sum is σ = 44660714352408. Its totient is φ = 8506130438400.

The previous prime is 21266166465053. The next prime is 21266166465253. The reversal of 21266166465220 is 2256466166212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 10436117328004 + 10830049137216 = 3230498^2 + 3290904^2 .

It is a super-2 number, since 2×21266166465220² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20490151 + ... + 21502990.

It is an arithmetic number, because the mean of its divisors is an integer number (1860863098017).

Almost surely, 2^{21266166465220} is an apocalyptic number.

21266166465220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21266166465220 is an abundant number, since it is smaller than the sum of its proper divisors (23394547887188).

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

21266166465220 is a wasteful number, since it uses less digits than its factorization.

21266166465220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42018471 (or 42018469 counting only the distinct ones).

The product of its (nonzero) digits is 2488320, while the sum is 49.

The spelling of 21266166465220 in words is "twenty-one trillion, two hundred sixty-six billion, one hundred sixty-six million, four hundred sixty-five thousand, two hundred twenty".