64691645 has 8 divisors (see below), whose sum is σ = 79523640. Its totient is φ = 50490880.

The previous prime is 64691639. The next prime is 64691657. The reversal of 64691645 is 54619646.

It can be written as a sum of positive squares in 4 ways, for example, as 515524 + 64176121 = 718^2 + 8011^2 .

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

It is not a de Polignac number, because 64691645 - 2⁴ = 64691629 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 157580 + ... + 157989.

It is an arithmetic number, because the mean of its divisors is an integer number (9940455).

Almost surely, 2^64691645 is an apocalyptic number.

It is an amenable number.

64691645 is a deficient number, since it is larger than the sum of its proper divisors (14831995).

64691645 is a wasteful number, since it uses less digits than its factorization.

64691645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 315615.

The product of its digits is 155520, while the sum is 41.

The square root of 64691645 is about 8043.1116491070. Note that the first 3 decimals coincide. The cubic root of 64691645 is about 401.4357673475.

The spelling of 64691645 in words is "sixty-four million, six hundred ninety-one thousand, six hundred forty-five".