21661339659 has 32 divisors (see below), whose sum is σ = 29525543424. Its totient is φ = 14122563840.

The previous prime is 21661339643. The next prime is 21661339673. The reversal of 21661339659 is 95693316612.

It is a happy number.

It is not a de Polignac number, because 21661339659 - 2⁴ = 21661339643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21661339619) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 29551257 + ... + 29551989.

It is an arithmetic number, because the mean of its divisors is an integer number (922673232).

Almost surely, 2^21661339659 is an apocalyptic number.

21661339659 is a deficient number, since it is larger than the sum of its proper divisors (7864203765).

21661339659 is a wasteful number, since it uses less digits than its factorization.

21661339659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1667.

The product of its digits is 1574640, while the sum is 51.

The spelling of 21661339659 in words is "twenty-one billion, six hundred sixty-one million, three hundred thirty-nine thousand, six hundred fifty-nine".