21661246561602 has 8 divisors (see below), whose sum is σ = 43322493123216. Its totient is φ = 7220415520532.

The previous prime is 21661246561601. The next prime is 21661246561609. The reversal of 21661246561602 is 20616564216612.

It is a happy number.

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

21661246561602 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21661246561601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1805103880128 + ... + 1805103880139.

It is an arithmetic number, because the mean of its divisors is an integer number (5415311640402).

Almost surely, 2^{21661246561602} is an apocalyptic number.

21661246561602 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21661246561602 is a wasteful number, since it uses less digits than its factorization.

21661246561602 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3610207760272.

The product of its (nonzero) digits is 1244160, while the sum is 48.

The spelling of 21661246561602 in words is "twenty-one trillion, six hundred sixty-one billion, two hundred forty-six million, five hundred sixty-one thousand, six hundred two".