21655212260 has 24 divisors (see below), whose sum is σ = 49610123136. Its totient is φ = 7874622560.

The previous prime is 21655212251. The next prime is 21655212307. The reversal of 21655212260 is 6221255612.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49216172 + ... + 49216611.

It is an arithmetic number, because the mean of its divisors is an integer number (2067088464).

Almost surely, 2^21655212260 is an apocalyptic number.

21655212260 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21655212260 is an abundant number, since it is smaller than the sum of its proper divisors (27954910876).

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

21655212260 is a wasteful number, since it uses less digits than its factorization.

21655212260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98432803 (or 98432801 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 32.

Adding to 21655212260 its reverse (6221255612), we get a palindrome (27876467872).

The spelling of 21655212260 in words is "twenty-one billion, six hundred fifty-five million, two hundred twelve thousand, two hundred sixty".