71220101661 has 8 divisors (see below), whose sum is σ = 105511261760. Its totient is φ = 47480067756.

The previous prime is 71220101651. The next prime is 71220101717. The reversal of 71220101661 is 16610102217.

It is a happy number.

It is not a de Polignac number, because 71220101661 - 2¹⁸ = 71219839517 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 2637781543 = 71220101661 / (7 + 1 + 2 + 2 + 0 + 1 + 0 + 1 + 6 + 6 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71220101651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1318890745 + ... + 1318890798.

It is an arithmetic number, because the mean of its divisors is an integer number (13188907720).

Almost surely, 2^71220101661 is an apocalyptic number.

It is an amenable number.

71220101661 is a deficient number, since it is larger than the sum of its proper divisors (34291160099).

71220101661 is a wasteful number, since it uses less digits than its factorization.

71220101661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2637781552 (or 2637781546 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

Adding to 71220101661 its reverse (16610102217), we get a palindrome (87830203878).

The spelling of 71220101661 in words is "seventy-one billion, two hundred twenty million, one hundred one thousand, six hundred sixty-one".