21655652840 has 32 divisors (see below), whose sum is σ = 49312277280. Its totient is φ = 8557895232.

The previous prime is 21655652839. The next prime is 21655652849. The reversal of 21655652840 is 4825655612.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21655652791 and 21655652800.

It is not an unprimeable number, because it can be changed into a prime (21655652849) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3258074 + ... + 3264713.

It is an arithmetic number, because the mean of its divisors is an integer number (1541008665).

Almost surely, 2^21655652840 is an apocalyptic number.

21655652840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21655652840 is an abundant number, since it is smaller than the sum of its proper divisors (27656624440).

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

21655652840 is a wasteful number, since it uses less digits than its factorization.

21655652840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6522881 (or 6522877 counting only the distinct ones).

The product of its (nonzero) digits is 576000, while the sum is 44.

The spelling of 21655652840 in words is "twenty-one billion, six hundred fifty-five million, six hundred fifty-two thousand, eight hundred forty".