638432820 has 48 divisors (see below), whose sum is σ = 1986237120. Its totient is φ = 170248608.

The previous prime is 638432803. The next prime is 638432849. The reversal of 638432820 is 28234836.

638432820 is nontrivially palindromic in base 8.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 590602 + ... + 591681.

It is an arithmetic number, because the mean of its divisors is an integer number (41379940).

Almost surely, 2^638432820 is an apocalyptic number.

638432820 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

638432820 is an abundant number, since it is smaller than the sum of its proper divisors (1347804300).

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

638432820 is a wasteful number, since it uses less digits than its factorization.

638432820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1182301 (or 1182293 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 638432820 is about 25267.2281819752. The cubic root of 638432820 is about 861.0698871266.

It can be divided in two parts, 6384 and 32820, that added together give a square (39204 = 198²).

The spelling of 638432820 in words is "six hundred thirty-eight million, four hundred thirty-two thousand, eight hundred twenty".