21161043660 has 48 divisors (see below), whose sum is σ = 62369395200. Its totient is φ = 5345947584.

The previous prime is 21161043653. The next prime is 21161043707. The reversal of 21161043660 is 6634016112.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9280020 + ... + 9282299.

It is an arithmetic number, because the mean of its divisors is an integer number (1299362400).

Almost surely, 2^21161043660 is an apocalyptic number.

21161043660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21161043660 is an abundant number, since it is smaller than the sum of its proper divisors (41208351540).

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

21161043660 is a wasteful number, since it uses less digits than its factorization.

21161043660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18562350 (or 18562348 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

Adding to 21161043660 its reverse (6634016112), we get a palindrome (27795059772).

The spelling of 21161043660 in words is "twenty-one billion, one hundred sixty-one million, forty-three thousand, six hundred sixty".