21555716005 has 16 divisors (see below), whose sum is σ = 26001399600. Its totient is φ = 17155031040.

The previous prime is 21555715997. The next prime is 21555716023. The reversal of 21555716005 is 50061755512.

It can be written as a sum of positive squares in 8 ways, for example, as 53012961 + 21502703044 = 7281^2 + 146638^2 .

It is not a de Polignac number, because 21555716005 - 2³ = 21555715997 is a prime.

It is a congruent number.

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, 1206981 + ... + 1224709.

It is an arithmetic number, because the mean of its divisors is an integer number (1625087475).

Almost surely, 2^21555716005 is an apocalyptic number.

It is an amenable number.

21555716005 is a deficient number, since it is larger than the sum of its proper divisors (4445683595).

21555716005 is a wasteful number, since it uses less digits than its factorization.

21555716005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18984.

The product of its (nonzero) digits is 52500, while the sum is 37.

The spelling of 21555716005 in words is "twenty-one billion, five hundred fifty-five million, seven hundred sixteen thousand, five".