19640645 has 8 divisors (see below), whose sum is σ = 23692056. Its totient is φ = 15630336.

The previous prime is 19640633. The next prime is 19640651. The reversal of 19640645 is 54604691.

It can be written as a sum of positive squares in 4 ways, for example, as 289444 + 19351201 = 538^2 + 4399^2 .

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 19640645 - 2¹⁸ = 19378501 is a prime.

It is a Duffinian 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, 9212 + ... + 11141.

It is an arithmetic number, because the mean of its divisors is an integer number (2961507).

Almost surely, 2^19640645 is an apocalyptic number.

It is an amenable number.

19640645 is a deficient number, since it is larger than the sum of its proper divisors (4051411).

19640645 is a wasteful number, since it uses less digits than its factorization.

19640645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20551.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 19640645 is about 4431.7767317409. The cubic root of 19640645 is about 269.8061937951.

The spelling of 19640645 in words is "nineteen million, six hundred forty thousand, six hundred forty-five".