21500111253721 has 8 divisors (see below), whose sum is σ = 21508917026688. Its totient is φ = 21491307180000.

The previous prime is 21500111253707. The next prime is 21500111253833. The reversal of 21500111253721 is 12735211100512.

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

It is a cyclic number.

It is not a de Polignac number, because 21500111253721 - 2⁹ = 21500111253209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21500111253701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25201381 + ... + 26040541.

It is an arithmetic number, because the mean of its divisors is an integer number (2688614628336).

Almost surely, 2^{21500111253721} is an apocalyptic number.

It is an amenable number.

21500111253721 is a deficient number, since it is larger than the sum of its proper divisors (8805772967).

21500111253721 is an equidigital number, since it uses as much as digits as its factorization.

21500111253721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849623.

The product of its (nonzero) digits is 4200, while the sum is 31.

The spelling of 21500111253721 in words is "twenty-one trillion, five hundred billion, one hundred eleven million, two hundred fifty-three thousand, seven hundred twenty-one".