21655404444644 has 12 divisors (see below), whose sum is σ = 37947019814844. Its totient is φ = 10813398783264.

The previous prime is 21655404444643. The next prime is 21655404444647. The reversal of 21655404444644 is 44644440455612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 11790227016100 + 9865177428544 = 3433690^2 + 3140888^2 .

It is a super-2 number, since 2×21655404444644² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21655404444643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3575856359 + ... + 3575862414.

It is an arithmetic number, because the mean of its divisors is an integer number (3162251651237).

Almost surely, 2^{21655404444644} is an apocalyptic number.

It is an amenable number.

21655404444644 is a deficient number, since it is larger than the sum of its proper divisors (16291615370200).

21655404444644 is a wasteful number, since it uses less digits than its factorization.

21655404444644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7151719534 (or 7151719532 counting only the distinct ones).

The product of its (nonzero) digits is 29491200, while the sum is 53.

The spelling of 21655404444644 in words is "twenty-one trillion, six hundred fifty-five billion, four hundred four million, four hundred forty-four thousand, six hundred forty-four".