21216224015461 has 2 divisors, whose sum is σ = 21216224015462. Its totient is φ = 21216224015460.

The previous prime is 21216224015419. The next prime is 21216224015489. The reversal of 21216224015461 is 16451042261212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17354881114561 + 3861342900900 = 4165919^2 + 1965030^2 .

It is a cyclic number.

It is not a de Polignac number, because 21216224015461 - 2³³ = 21207634080869 is a prime.

It is a super-2 number, since 2×21216224015461² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21216224015461.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21216224010461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608112007730 + 10608112007731.

It is an arithmetic number, because the mean of its divisors is an integer number (10608112007731).

Almost surely, 2^{21216224015461} is an apocalyptic number.

It is an amenable number.

21216224015461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216224015461 is an equidigital number, since it uses as much as digits as its factorization.

21216224015461 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46080, while the sum is 37.

Adding to 21216224015461 its reverse (16451042261212), we get a palindrome (37667266276673).

The spelling of 21216224015461 in words is "twenty-one trillion, two hundred sixteen billion, two hundred twenty-four million, fifteen thousand, four hundred sixty-one".