21621415563316 has 6 divisors (see below), whose sum is σ = 37837477235810. Its totient is φ = 10810707781656.

The previous prime is 21621415563299. The next prime is 21621415563331. The reversal of 21621415563316 is 61336551412612.

It can be written as a sum of positive squares in only one way, i.e., 17867106302500 + 3754309260816 = 4226950^2 + 1937604^2 .

It is a super-2 number, since 2×21621415563316² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2702676945411 + ... + 2702676945418.

Almost surely, 2^{21621415563316} is an apocalyptic number.

It is an amenable number.

21621415563316 is a deficient number, since it is larger than the sum of its proper divisors (16216061672494).

21621415563316 is a wasteful number, since it uses less digits than its factorization.

21621415563316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5405353890833 (or 5405353890831 counting only the distinct ones).

The product of its digits is 777600, while the sum is 46.

Adding to 21621415563316 its reverse (61336551412612), we get a palindrome (82957966975928).

The spelling of 21621415563316 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred fifteen million, five hundred sixty-three thousand, three hundred sixteen".