21655416002261 has 16 divisors (see below), whose sum is σ = 23435721550080. Its totient is φ = 19932072437760.

The previous prime is 21655416002257. The next prime is 21655416002267. The reversal of 21655416002261 is 16220061455612.

It is not a de Polignac number, because 21655416002261 - 2² = 21655416002257 is a prime.

It is a super-2 number, since 2×21655416002261² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21655416002267) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9757820 + ... + 11769701.

It is an arithmetic number, because the mean of its divisors is an integer number (1464732596880).

Almost surely, 2^{21655416002261} is an apocalyptic number.

It is an amenable number.

21655416002261 is a deficient number, since it is larger than the sum of its proper divisors (1780305547819).

21655416002261 is a wasteful number, since it uses less digits than its factorization.

21655416002261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21528844.

The product of its (nonzero) digits is 172800, while the sum is 41.

Adding to 21655416002261 its reverse (16220061455612), we get a palindrome (37875477457873).

The spelling of 21655416002261 in words is "twenty-one trillion, six hundred fifty-five billion, four hundred sixteen million, two thousand, two hundred sixty-one".