21625639465 has 4 divisors (see below), whose sum is σ = 25950767364. Its totient is φ = 17300511568.

The previous prime is 21625639423. The next prime is 21625639487. The reversal of 21625639465 is 56493652612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3023680144 + 18601959321 = 54988^2 + 136389^2 .

It is a cyclic number.

It is not a de Polignac number, because 21625639465 - 2⁷ = 21625639337 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2162563942 + ... + 2162563951.

It is an arithmetic number, because the mean of its divisors is an integer number (6487691841).

Almost surely, 2^21625639465 is an apocalyptic number.

It is an amenable number.

21625639465 is a deficient number, since it is larger than the sum of its proper divisors (4325127899).

21625639465 is an equidigital number, since it uses as much as digits as its factorization.

21625639465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4325127898.

The product of its digits is 2332800, while the sum is 49.

The spelling of 21625639465 in words is "twenty-one billion, six hundred twenty-five million, six hundred thirty-nine thousand, four hundred sixty-five".