101565721 has 4 divisors (see below), whose sum is σ = 101586100. Its totient is φ = 101545344.

The previous prime is 101565719. The next prime is 101565749. The reversal of 101565721 is 127565101.

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

It can be written as a sum of positive squares in 2 ways, for example, as 97239321 + 4326400 = 9861^2 + 2080^2 .

It is a cyclic number.

It is not a de Polignac number, because 101565721 - 2¹ = 101565719 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 101565721.

It is not an unprimeable number, because it can be changed into a prime (101565781) 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, 2845 + ... + 14533.

It is an arithmetic number, because the mean of its divisors is an integer number (25396525).

Almost surely, 2^101565721 is an apocalyptic number.

It is an amenable number.

101565721 is a deficient number, since it is larger than the sum of its proper divisors (20379).

101565721 is an equidigital number, since it uses as much as digits as its factorization.

101565721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20378.

The product of its (nonzero) digits is 2100, while the sum is 28.

The square root of 101565721 is about 10077.9819904582. The cubic root of 101565721 is about 466.5688268242.

The spelling of 101565721 in words is "one hundred one million, five hundred sixty-five thousand, seven hundred twenty-one".