21261719265 has 8 divisors (see below), whose sum is σ = 34018750848. Its totient is φ = 11339583600.

The previous prime is 21261719249. The next prime is 21261719267. The reversal of 21261719265 is 56291716212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21261719265 - 2⁴ = 21261719249 is a prime.

It is a super-2 number, since 2×21261719265² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21261719267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 708723961 + ... + 708723990.

It is an arithmetic number, because the mean of its divisors is an integer number (4252343856).

Almost surely, 2^21261719265 is an apocalyptic number.

It is an amenable number.

21261719265 is a deficient number, since it is larger than the sum of its proper divisors (12757031583).

21261719265 is a wasteful number, since it uses less digits than its factorization.

21261719265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1417447959.

The product of its digits is 90720, while the sum is 42.

The spelling of 21261719265 in words is "twenty-one billion, two hundred sixty-one million, seven hundred nineteen thousand, two hundred sixty-five".