21516650021 has 8 divisors (see below), whose sum is σ = 22406016000. Its totient is φ = 20637111600.

The previous prime is 21516650017. The next prime is 21516650033. The reversal of 21516650021 is 12005661512.

It is a happy number.

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 21516650021 - 2² = 21516650017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21516650011) 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, 2452421 + ... + 2461178.

It is an arithmetic number, because the mean of its divisors is an integer number (2800752000).

Almost surely, 2^21516650021 is an apocalyptic number.

It is an amenable number.

21516650021 is a deficient number, since it is larger than the sum of its proper divisors (889365979).

21516650021 is a wasteful number, since it uses less digits than its factorization.

21516650021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4913779.

The product of its (nonzero) digits is 3600, while the sum is 29.

The spelling of 21516650021 in words is "twenty-one billion, five hundred sixteen million, six hundred fifty thousand, twenty-one".