644550420 has 24 divisors (see below), whose sum is σ = 1804741344. Its totient is φ = 171880096.

The previous prime is 644550407. The next prime is 644550443. The reversal of 644550420 is 24055446.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5371194 + ... + 5371313.

It is an arithmetic number, because the mean of its divisors is an integer number (75197556).

Almost surely, 2^644550420 is an apocalyptic number.

644550420 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644550420 is an abundant number, since it is smaller than the sum of its proper divisors (1160190924).

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

644550420 is a wasteful number, since it uses less digits than its factorization.

644550420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10742519 (or 10742517 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 30.

The square root of 644550420 is about 25387.9975579013. The cubic root of 644550420 is about 863.8114675655.

It can be divided in two parts, 6445 and 50420, that added together give a palindrome (56865).

The spelling of 644550420 in words is "six hundred forty-four million, five hundred fifty thousand, four hundred twenty".