18640621391 has 8 divisors (see below), whose sum is σ = 21312187680. Its totient is φ = 15971210208.

The previous prime is 18640621381. The next prime is 18640621393. The reversal of 18640621391 is 19312604681.

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 18640621391 - 2²² = 18636427087 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18640621393) 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, 520196 + ... + 554873.

It is an arithmetic number, because the mean of its divisors is an integer number (2664023460).

Almost surely, 2^18640621391 is an apocalyptic number.

18640621391 is a deficient number, since it is larger than the sum of its proper divisors (2671566289).

18640621391 is a wasteful number, since it uses less digits than its factorization.

18640621391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077553.

The product of its (nonzero) digits is 62208, while the sum is 41.

The spelling of 18640621391 in words is "eighteen billion, six hundred forty million, six hundred twenty-one thousand, three hundred ninety-one".