820406280509 has 4 divisors (see below), whose sum is σ = 856076118816. Its totient is φ = 784736442204.

The previous prime is 820406280479. The next prime is 820406280539. The reversal of 820406280509 is 905082604028.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (820406280479) and next prime (820406280539).

It is not a de Polignac number, because 820406280509 - 2³⁶ = 751686803773 is a prime.

It is a super-2 number, since 2×820406280509² (a number of 25 digits) contains 22 as substring.

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 820406280509.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820406280539) 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, 17834919119 + ... + 17834919164.

It is an arithmetic number, because the mean of its divisors is an integer number (214019029704).

Almost surely, 2^820406280509 is an apocalyptic number.

It is an amenable number.

820406280509 is a deficient number, since it is larger than the sum of its proper divisors (35669838307).

820406280509 is a wasteful number, since it uses less digits than its factorization.

820406280509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35669838306.

The product of its (nonzero) digits is 276480, while the sum is 44.

The spelling of 820406280509 in words is "eight hundred twenty billion, four hundred six million, two hundred eighty thousand, five hundred nine".