21661016562120 has 128 divisors (see below), whose sum is σ = 70119237081600. Its totient is φ = 5321467014144.

The previous prime is 21661016562071. The next prime is 21661016562131. The reversal of 21661016562120 is 2126561016612.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12845712 + ... + 14433791.

It is an arithmetic number, because the mean of its divisors is an integer number (547806539700).

Almost surely, 2^{21661016562120} is an apocalyptic number.

21661016562120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21661016562120 is an abundant number, since it is smaller than the sum of its proper divisors (48458220519480).

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

21661016562120 is a wasteful number, since it uses less digits than its factorization.

21661016562120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27280039 (or 27280035 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 39.

Adding to 21661016562120 its reverse (2126561016612), we get a palindrome (23787577578732).

The spelling of 21661016562120 in words is "twenty-one trillion, six hundred sixty-one billion, sixteen million, five hundred sixty-two thousand, one hundred twenty".