21661353054 has 48 divisors (see below), whose sum is σ = 51311810160. Its totient is φ = 6549655680.

The previous prime is 21661353041. The next prime is 21661353107. The reversal of 21661353054 is 45035316612.

21661353054 is a `hidden beast` number, since 2 + 1 + 6 + 613 + 5 + 30 + 5 + 4 = 666.

It is a super-2 number, since 2×21661353054² (a number of 21 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 23 ways as a sum of consecutive naturals, for example, 29209 + ... + 210180.

It is an arithmetic number, because the mean of its divisors is an integer number (1068996045).

Almost surely, 2^21661353054 is an apocalyptic number.

21661353054 is an abundant number, since it is smaller than the sum of its proper divisors (29650457106).

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

21661353054 is a wasteful number, since it uses less digits than its factorization.

21661353054 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239865 (or 239862 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

Adding to 21661353054 its reverse (45035316612), we get a palindrome (66696669666).

The spelling of 21661353054 in words is "twenty-one billion, six hundred sixty-one million, three hundred fifty-three thousand, fifty-four".