21661020450620 has 24 divisors (see below), whose sum is σ = 45491300915424. Its totient is φ = 8663806662336.

The previous prime is 21661020450577. The next prime is 21661020450679. The reversal of 21661020450620 is 2605402016612.

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, 37299527 + ... + 37875806.

It is an arithmetic number, because the mean of its divisors is an integer number (1895470871476).

Almost surely, 2^{21661020450620} is an apocalyptic number.

21661020450620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21661020450620 is an abundant number, since it is smaller than the sum of its proper divisors (23830280464804).

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

21661020450620 is a wasteful number, since it uses less digits than its factorization.

21661020450620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75189749 (or 75189747 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 35.

The spelling of 21661020450620 in words is "twenty-one trillion, six hundred sixty-one billion, twenty million, four hundred fifty thousand, six hundred twenty".