21494240665 has 16 divisors (see below), whose sum is σ = 26111248128. Its totient is φ = 16983404416.

The previous prime is 21494240633. The next prime is 21494240681. The reversal of 21494240665 is 56604249412.

It is a cyclic number.

It is not a de Polignac number, because 21494240665 - 2⁵ = 21494240633 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2442864 + ... + 2451646.

It is an arithmetic number, because the mean of its divisors is an integer number (1631953008).

Almost surely, 2^21494240665 is an apocalyptic number.

It is an amenable number.

21494240665 is a deficient number, since it is larger than the sum of its proper divisors (4617007463).

21494240665 is an equidigital number, since it uses as much as digits as its factorization.

21494240665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14768.

The product of its (nonzero) digits is 414720, while the sum is 43.

The spelling of 21494240665 in words is "twenty-one billion, four hundred ninety-four million, two hundred forty thousand, six hundred sixty-five".