643551077 has 8 divisors (see below), whose sum is σ = 693407064. Its totient is φ = 593745408.

The previous prime is 643551067. The next prime is 643551091. The reversal of 643551077 is 770155346.

It can be written as a sum of positive squares in 4 ways, for example, as 8561476 + 634989601 = 2926^2 + 25199^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643551077 - 2⁸ = 643550821 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 643551077.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643551067) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16493 + ... + 39485.

It is an arithmetic number, because the mean of its divisors is an integer number (86675883).

Almost surely, 2^643551077 is an apocalyptic number.

It is an amenable number.

643551077 is a deficient number, since it is larger than the sum of its proper divisors (49855987).

643551077 is a wasteful number, since it uses less digits than its factorization.

643551077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25159.

The product of its (nonzero) digits is 88200, while the sum is 38.

The square root of 643551077 is about 25368.3085167301. The cubic root of 643551077 is about 863.3648045686.

The spelling of 643551077 in words is "six hundred forty-three million, five hundred fifty-one thousand, seventy-seven".