21661042630016 has 64 divisors (see below), whose sum is σ = 45429370776000. Its totient is φ = 10259294593536.

The previous prime is 21661042629943. The next prime is 21661042630021. The reversal of 21661042630016 is 61003624016612.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (38).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20464655 + ... + 21497073.

It is an arithmetic number, because the mean of its divisors is an integer number (709833918375).

Almost surely, 2^{21661042630016} is an apocalyptic number.

It is an amenable number.

21661042630016 is an abundant number, since it is smaller than the sum of its proper divisors (23768328145984).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21661042630016 is a wasteful number, since it uses less digits than its factorization.

21661042630016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1041079 (or 1041067 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 38.

Adding to 21661042630016 its reverse (61003624016612), we get a palindrome (82664666646628).

The spelling of 21661042630016 in words is "twenty-one trillion, six hundred sixty-one billion, forty-two million, six hundred thirty thousand, sixteen".