21216211615493 has 2 divisors, whose sum is σ = 21216211615494. Its totient is φ = 21216211615492.

The previous prime is 21216211615483. The next prime is 21216211615559. The reversal of 21216211615493 is 39451611261212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11226775007044 + 9989436608449 = 3350638^2 + 3160607^2 .

It is a cyclic number.

It is not a de Polignac number, because 21216211615493 - 2¹⁴ = 21216211599109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21216211615433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608105807746 + 10608105807747.

It is an arithmetic number, because the mean of its divisors is an integer number (10608105807747).

Almost surely, 2^{21216211615493} is an apocalyptic number.

It is an amenable number.

21216211615493 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216211615493 is an equidigital number, since it uses as much as digits as its factorization.

21216211615493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 44.

The spelling of 21216211615493 in words is "twenty-one trillion, two hundred sixteen billion, two hundred eleven million, six hundred fifteen thousand, four hundred ninety-three".