646622551 has 4 divisors (see below), whose sum is σ = 647743792. Its totient is φ = 645501312.

The previous prime is 646622549. The next prime is 646622563. The reversal of 646622551 is 155226646.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 646622551 - 2¹ = 646622549 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 646622551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646622651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559755 + ... + 560908.

It is an arithmetic number, because the mean of its divisors is an integer number (161935948).

Almost surely, 2^646622551 is an apocalyptic number.

646622551 is a deficient number, since it is larger than the sum of its proper divisors (1121241).

646622551 is a wasteful number, since it uses less digits than its factorization.

646622551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121240.

The product of its digits is 86400, while the sum is 37.

The square root of 646622551 is about 25428.7740758378. The cubic root of 646622551 is about 864.7361512756.

The spelling of 646622551 in words is "six hundred forty-six million, six hundred twenty-two thousand, five hundred fifty-one".