21661616446 has 8 divisors (see below), whose sum is σ = 33248062584. Its totient is φ = 10578928920.

The previous prime is 21661616437. The next prime is 21661616491. The reversal of 21661616446 is 64461616612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a congruent 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, 125939545 + ... + 125939716.

It is an arithmetic number, because the mean of its divisors is an integer number (4156007823).

Almost surely, 2^21661616446 is an apocalyptic number.

21661616446 is a deficient number, since it is larger than the sum of its proper divisors (11586446138).

21661616446 is a wasteful number, since it uses less digits than its factorization.

21661616446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251879306.

The product of its digits is 248832, while the sum is 43.

The spelling of 21661616446 in words is "twenty-one billion, six hundred sixty-one million, six hundred sixteen thousand, four hundred forty-six".