820291905 has 48 divisors (see below), whose sum is σ = 1523733120. Its totient is φ = 406761984.

The previous prime is 820291903. The next prime is 820291919. The reversal of 820291905 is 509192028.

It is not a de Polignac number, because 820291905 - 2¹ = 820291903 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 820291905.

It is not an unprimeable number, because it can be changed into a prime (820291903) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 57036 + ... + 69954.

It is an arithmetic number, because the mean of its divisors is an integer number (31744440).

Almost surely, 2^820291905 is an apocalyptic number.

820291905 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

820291905 is a deficient number, since it is larger than the sum of its proper divisors (703441215).

820291905 is a wasteful number, since it uses less digits than its factorization.

820291905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13030 (or 13027 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 820291905 is about 28640.7385554214. The cubic root of 820291905 is about 936.1012142630.

The spelling of 820291905 in words is "eight hundred twenty million, two hundred ninety-one thousand, nine hundred five".