645947501 has 4 divisors (see below), whose sum is σ = 647634432. Its totient is φ = 644260572.

The previous prime is 645947473. The next prime is 645947509. The reversal of 645947501 is 105749546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645947501 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645947509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 842891 + ... + 843656.

It is an arithmetic number, because the mean of its divisors is an integer number (161908608).

Almost surely, 2^645947501 is an apocalyptic number.

It is an amenable number.

645947501 is a deficient number, since it is larger than the sum of its proper divisors (1686931).

645947501 is a wasteful number, since it uses less digits than its factorization.

645947501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1686930.

The product of its (nonzero) digits is 151200, while the sum is 41.

The square root of 645947501 is about 25415.4972605298. The cubic root of 645947501 is about 864.4351289918.

The spelling of 645947501 in words is "six hundred forty-five million, nine hundred forty-seven thousand, five hundred one".