66620640 has 48 divisors (see below), whose sum is σ = 209856528. Its totient is φ = 17765376.

The previous prime is 66620633. The next prime is 66620647. The reversal of 66620640 is 4602666.

66620640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (66620633) and next prime (66620647).

It is a tau number, because it is divible by the number of its divisors (48).

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

It is a junction number, because it is equal to n+sod(n) for n = 66620598 and 66620607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66620647) 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 7 ways as a sum of consecutive naturals, for example, 68917 + ... + 69876.

It is an arithmetic number, because the mean of its divisors is an integer number (4372011).

Almost surely, 2^66620640 is an apocalyptic number.

66620640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66620640 is an abundant number, since it is smaller than the sum of its proper divisors (143235888).

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

66620640 is a wasteful number, since it uses less digits than its factorization.

66620640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138811 (or 138803 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 30.

The square root of 66620640 is about 8162.1467764308. The cubic root of 66620640 is about 405.3867970606.

The spelling of 66620640 in words is "sixty-six million, six hundred twenty thousand, six hundred forty".