820420637 has 4 divisors (see below), whose sum is σ = 820672476. Its totient is φ = 820168800.

The previous prime is 820420633. The next prime is 820420639. The reversal of 820420637 is 736024028.

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

It can be written as a sum of positive squares in 2 ways, for example, as 48636676 + 771783961 = 6974^2 + 27781^2 .

It is a cyclic number.

It is not a de Polignac number, because 820420637 - 2² = 820420633 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820420631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120968 + ... + 127569.

It is an arithmetic number, because the mean of its divisors is an integer number (205168119).

Almost surely, 2^820420637 is an apocalyptic number.

It is an amenable number.

820420637 is a deficient number, since it is larger than the sum of its proper divisors (251839).

820420637 is a wasteful number, since it uses less digits than its factorization.

820420637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251838.

The product of its (nonzero) digits is 16128, while the sum is 32.

The square root of 820420637 is about 28642.9858255036. The cubic root of 820420637 is about 936.1501805222.

The spelling of 820420637 in words is "eight hundred twenty million, four hundred twenty thousand, six hundred thirty-seven".