644663326264020 has 192 divisors, whose sum is σ = 2292156406310400. Its totient is φ = 147350323031040.

The previous prime is 644663326264007. The next prime is 644663326264021. The reversal of 644663326264020 is 20462623366446.

644663326264020 is a `hidden beast` number, since 6 + 4 + 4 + 6 + 6 + 3 + 3 + 2 + 626 + 4 + 0 + 2 + 0 = 666.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644663326264021) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 468490366 + ... + 469864394.

It is an arithmetic number, because the mean of its divisors is an integer number (11938314616200).

Almost surely, 2^{644663326264020} is an apocalyptic number.

644663326264020 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644663326264020 is an abundant number, since it is smaller than the sum of its proper divisors (1647493080046380).

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

644663326264020 is a wasteful number, since it uses less digits than its factorization.

644663326264020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1498175 (or 1498167 counting only the distinct ones).

The product of its (nonzero) digits is 35831808, while the sum is 54.

The spelling of 644663326264020 in words is "six hundred forty-four trillion, six hundred sixty-three billion, three hundred twenty-six million, two hundred sixty-four thousand, twenty".