72020010565661 has 4 divisors (see below), whose sum is σ = 72020030550492. Its totient is φ = 72019990580832.

The previous prime is 72020010565637. The next prime is 72020010565703. The reversal of 72020010565661 is 16656501002027.

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 26825987543161 + 45194023022500 = 5179381^2 + 6722650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72020010565661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72020010561661) 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 3 ways as a sum of consecutive naturals, for example, 2916680 + ... + 12350993.

It is an arithmetic number, because the mean of its divisors is an integer number (18005007637623).

Almost surely, 2^{72020010565661} is an apocalyptic number.

It is an amenable number.

72020010565661 is a deficient number, since it is larger than the sum of its proper divisors (19984831).

72020010565661 is a wasteful number, since it uses less digits than its factorization.

72020010565661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19984830.

The product of its (nonzero) digits is 151200, while the sum is 41.

Adding to 72020010565661 its reverse (16656501002027), we get a palindrome (88676511567688).

The spelling of 72020010565661 in words is "seventy-two trillion, twenty billion, ten million, five hundred sixty-five thousand, six hundred sixty-one".