21951394083261 has 24 divisors (see below), whose sum is σ = 31776923393280. Its totient is φ = 14602259189376.

The previous prime is 21951394083259. The next prime is 21951394083277. The reversal of 21951394083261 is 16238049315912.

21951394083261 is a `hidden beast` number, since 2 + 1 + 9 + 513 + 9 + 40 + 83 + 2 + 6 + 1 = 666.

It is not a de Polignac number, because 21951394083261 - 2¹ = 21951394083259 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21951394083198 and 21951394083207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21951394081261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 44013061 + ... + 44509013.

It is an arithmetic number, because the mean of its divisors is an integer number (1324038474720).

Almost surely, 2^{21951394083261} is an apocalyptic number.

It is an amenable number.

21951394083261 is a deficient number, since it is larger than the sum of its proper divisors (9825529310019).

21951394083261 is a wasteful number, since it uses less digits than its factorization.

21951394083261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506705 (or 506702 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 54.

The spelling of 21951394083261 in words is "twenty-one trillion, nine hundred fifty-one billion, three hundred ninety-four million, eighty-three thousand, two hundred sixty-one".