820138770 has 160 divisors (see below), whose sum is σ = 2436920640. Its totient is φ = 196248960.

The previous prime is 820138751. The next prime is 820138817. The reversal of 820138770 is 77831028.

820138770 is a `hidden beast` number, since 8 + 201 + 387 + 70 = 666.

It is a super-2 number, since 2×820138770² = 1345255204114225800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 738976 + ... + 740084.

It is an arithmetic number, because the mean of its divisors is an integer number (15230754).

Almost surely, 2^820138770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 820138770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1218460320).

820138770 is an abundant number, since it is smaller than the sum of its proper divisors (1616781870).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

820138770 is a wasteful number, since it uses less digits than its factorization.

820138770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1222 (or 1213 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The square root of 820138770 is about 28638.0650533516. The cubic root of 820138770 is about 936.0429590737.

Adding to 820138770 its reverse (77831028), we get a palindrome (897969798).

It can be divided in two parts, 8201 and 38770, that added together give a triangular number (46971 = T₃₀₆).

The spelling of 820138770 in words is "eight hundred twenty million, one hundred thirty-eight thousand, seven hundred seventy".