21660534427451 has 2 divisors, whose sum is σ = 21660534427452. Its totient is φ = 21660534427450.

The previous prime is 21660534427447. The next prime is 21660534427471. The reversal of 21660534427451 is 15472443506612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21660534427451 - 2² = 21660534427447 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21660534427451.

It is not a weakly prime, because it can be changed into another prime (21660534427471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10830267213725 + 10830267213726.

It is an arithmetic number, because the mean of its divisors is an integer number (10830267213726).

Almost surely, 2^{21660534427451} is an apocalyptic number.

21660534427451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21660534427451 is an equidigital number, since it uses as much as digits as its factorization.

21660534427451 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4838400, while the sum is 50.

The spelling of 21660534427451 in words is "twenty-one trillion, six hundred sixty billion, five hundred thirty-four million, four hundred twenty-seven thousand, four hundred fifty-one".