21661465732428 has 24 divisors (see below), whose sum is σ = 53203600045120. Its totient is φ = 6840462862800.

The previous prime is 21661465732391. The next prime is 21661465732429. The reversal of 21661465732428 is 82423756416612.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is not an unprimeable number, because it can be changed into a prime (21661465732429) 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, 47503214098 + ... + 47503214553.

Almost surely, 2^{21661465732428} is an apocalyptic number.

It is an amenable number.

21661465732428 is an abundant number, since it is smaller than the sum of its proper divisors (31542134312692).

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

21661465732428 is a wasteful number, since it uses less digits than its factorization.

21661465732428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95006428677 (or 95006428675 counting only the distinct ones).

The product of its digits is 23224320, while the sum is 57.

The spelling of 21661465732428 in words is "twenty-one trillion, six hundred sixty-one billion, four hundred sixty-five million, seven hundred thirty-two thousand, four hundred twenty-eight".