21761166661267 has 4 divisors (see below), whose sum is σ = 23739454539576. Its totient is φ = 19782878782960.

The previous prime is 21761166661253. The next prime is 21761166661291. The reversal of 21761166661267 is 76216666116712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21761166661267 - 2¹⁹ = 21761166136979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21761166661237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 989143939138 + ... + 989143939159.

It is an arithmetic number, because the mean of its divisors is an integer number (5934863634894).

Almost surely, 2^{21761166661267} is an apocalyptic number.

21761166661267 is a deficient number, since it is larger than the sum of its proper divisors (1978287878309).

21761166661267 is a wasteful number, since it uses less digits than its factorization.

21761166661267 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1978287878308.

The product of its digits is 9144576, while the sum is 58.

Subtracting 21761166661267 from its reverse (76216666116712), we obtain a palindrome (54455499455445).

The spelling of 21761166661267 in words is "twenty-one trillion, seven hundred sixty-one billion, one hundred sixty-six million, six hundred sixty-one thousand, two hundred sixty-seven".