820840749 has 4 divisors (see below), whose sum is σ = 1094454336. Its totient is φ = 547227164.

The previous prime is 820840729. The next prime is 820840753. The reversal of 820840749 is 947048028.

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 a cyclic number.

It is not a de Polignac number, because 820840749 - 2¹¹ = 820838701 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 820840749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820840729) 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, 136806789 + ... + 136806794.

It is an arithmetic number, because the mean of its divisors is an integer number (273613584).

Almost surely, 2^820840749 is an apocalyptic number.

It is an amenable number.

820840749 is a deficient number, since it is larger than the sum of its proper divisors (273613587).

820840749 is a wasteful number, since it uses less digits than its factorization.

820840749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273613586.

The product of its (nonzero) digits is 129024, while the sum is 42.

The square root of 820840749 is about 28650.3184799052. The cubic root of 820840749 is about 936.3099444270.

The spelling of 820840749 in words is "eight hundred twenty million, eight hundred forty thousand, seven hundred forty-nine".