21661020453550 has 48 divisors (see below), whose sum is σ = 40726700467200. Its totient is φ = 8570893023200.

The previous prime is 21661020453503. The next prime is 21661020453551. The reversal of 21661020453550 is 5535402016612.

It is a super-2 number, since 2×21661020453550² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661020453551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4626220 + ... + 8045119.

It is an arithmetic number, because the mean of its divisors is an integer number (848472926400).

Almost surely, 2^{21661020453550} is an apocalyptic number.

21661020453550 is a deficient number, since it is larger than the sum of its proper divisors (19065680013650).

21661020453550 is a wasteful number, since it uses less digits than its factorization.

21661020453550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12671721 (or 12671716 counting only the distinct ones).

The product of its (nonzero) digits is 216000, while the sum is 40.

The spelling of 21661020453550 in words is "twenty-one trillion, six hundred sixty-one billion, twenty million, four hundred fifty-three thousand, five hundred fifty".