820428187291 has 4 divisors (see below), whose sum is σ = 820430144872. Its totient is φ = 820426229712.

The previous prime is 820428187283. The next prime is 820428187301. The reversal of 820428187291 is 192781824028.

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

It is a cyclic number.

It is not a de Polignac number, because 820428187291 - 2³ = 820428187283 is a prime.

It is a super-3 number, since 3×820428187291³ (a number of 37 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (820428187211) 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, 67026 + ... + 1282711.

It is an arithmetic number, because the mean of its divisors is an integer number (205107536218).

Almost surely, 2^820428187291 is an apocalyptic number.

820428187291 is a deficient number, since it is larger than the sum of its proper divisors (1957581).

820428187291 is a wasteful number, since it uses less digits than its factorization.

820428187291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1957580.

The product of its (nonzero) digits is 1032192, while the sum is 52.

The spelling of 820428187291 in words is "eight hundred twenty billion, four hundred twenty-eight million, one hundred eighty-seven thousand, two hundred ninety-one".