820019564661 has 16 divisors (see below), whose sum is σ = 1192771353600. Its totient is φ = 496975044720.

The previous prime is 820019564659. The next prime is 820019564687. The reversal of 820019564661 is 166465910028.

It is not a de Polignac number, because 820019564661 - 2¹ = 820019564659 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 820019564661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820019564641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3934276 + ... + 4137458.

It is an arithmetic number, because the mean of its divisors is an integer number (74548209600).

Almost surely, 2^820019564661 is an apocalyptic number.

It is an amenable number.

820019564661 is a deficient number, since it is larger than the sum of its proper divisors (372751788939).

820019564661 is a wasteful number, since it uses less digits than its factorization.

820019564661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325496.

The product of its (nonzero) digits is 622080, while the sum is 48.

The spelling of 820019564661 in words is "eight hundred twenty billion, nineteen million, five hundred sixty-four thousand, six hundred sixty-one".