21661550524 has 24 divisors (see below), whose sum is σ = 38304236880. Its totient is φ = 10718054784.

The previous prime is 21661550503. The next prime is 21661550543. The reversal of 21661550524 is 42505516612.

It is a super-2 number, since 2×21661550524² (a number of 21 digits) contains 22 as substring.

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, 80622 + ... + 223210.

It is an arithmetic number, because the mean of its divisors is an integer number (1596009870).

Almost surely, 2^21661550524 is an apocalyptic number.

It is an amenable number.

21661550524 is a deficient number, since it is larger than the sum of its proper divisors (16642686356).

21661550524 is a wasteful number, since it uses less digits than its factorization.

21661550524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142989 (or 142987 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 37.

The spelling of 21661550524 in words is "twenty-one billion, six hundred sixty-one million, five hundred fifty thousand, five hundred twenty-four".