21665723465 has 8 divisors (see below), whose sum is σ = 27367229760. Its totient is φ = 16420337712.

The previous prime is 21665723459. The next prime is 21665723467. The reversal of 21665723465 is 56432756612.

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 21665723465 - 2²² = 21661529161 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21665723467) 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, 114030029 + ... + 114030218.

It is an arithmetic number, because the mean of its divisors is an integer number (3420903720).

Almost surely, 2^21665723465 is an apocalyptic number.

It is an amenable number.

21665723465 is a deficient number, since it is larger than the sum of its proper divisors (5701506295).

21665723465 is a wasteful number, since it uses less digits than its factorization.

21665723465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228060271.

The product of its digits is 1814400, while the sum is 47.

The spelling of 21665723465 in words is "twenty-one billion, six hundred sixty-five million, seven hundred twenty-three thousand, four hundred sixty-five".