21655011449 has 4 divisors (see below), whose sum is σ = 21813077364. Its totient is φ = 21496945536.

The previous prime is 21655011439. The next prime is 21655011473. The reversal of 21655011449 is 94411055612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17860451449 + 3794560000 = 133643^2 + 61600^2 .

It is a cyclic number.

It is not a de Polignac number, because 21655011449 - 2¹⁶ = 21654945913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21655011419) 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, 79032752 + ... + 79033025.

It is an arithmetic number, because the mean of its divisors is an integer number (5453269341).

Almost surely, 2^21655011449 is an apocalyptic number.

It is an amenable number.

21655011449 is a deficient number, since it is larger than the sum of its proper divisors (158065915).

21655011449 is a wasteful number, since it uses less digits than its factorization.

21655011449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158065914.

The product of its (nonzero) digits is 43200, while the sum is 38.

The spelling of 21655011449 in words is "twenty-one billion, six hundred fifty-five million, eleven thousand, four hundred forty-nine".