21660561624243 has 64 divisors (see below), whose sum is σ = 31629035520000. Its totient is φ = 13129815803904.

The previous prime is 21660561624193. The next prime is 21660561624293. The reversal of 21660561624243 is 34242616506612.

It is an interprime number because it is at equal distance from previous prime (21660561624193) and next prime (21660561624293).

It is not a de Polignac number, because 21660561624243 - 2¹³ = 21660561616051 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21660561624192 and 21660561624201.

It is not an unprimeable number, because it can be changed into a prime (21660561624293) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 809454898 + ... + 809481656.

It is an arithmetic number, because the mean of its divisors is an integer number (494203680000).

Almost surely, 2^{21660561624243} is an apocalyptic number.

21660561624243 is a deficient number, since it is larger than the sum of its proper divisors (9968473895757).

21660561624243 is a wasteful number, since it uses less digits than its factorization.

21660561624243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29844.

The product of its (nonzero) digits is 2488320, while the sum is 48.

The spelling of 21660561624243 in words is "twenty-one trillion, six hundred sixty billion, five hundred sixty-one million, six hundred twenty-four thousand, two hundred forty-three".