21221405665015 has 16 divisors (see below), whose sum is σ = 27833464131840. Its totient is φ = 15463035624960.

The previous prime is 21221405665003. The next prime is 21221405665021. The reversal of 21221405665015 is 51056650412212.

It is not a de Polignac number, because 21221405665015 - 2²³ = 21221397276407 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4026829560 + ... + 4026834829.

It is an arithmetic number, because the mean of its divisors is an integer number (1739591508240).

Almost surely, 2^{21221405665015} is an apocalyptic number.

21221405665015 is a deficient number, since it is larger than the sum of its proper divisors (6612058466825).

21221405665015 is a wasteful number, since it uses less digits than its factorization.

21221405665015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8053664442.

The product of its (nonzero) digits is 144000, while the sum is 40.

The spelling of 21221405665015 in words is "twenty-one trillion, two hundred twenty-one billion, four hundred five million, six hundred sixty-five thousand, fifteen".