21661042215502 has 4 divisors (see below), whose sum is σ = 32491563323256. Its totient is φ = 10830521107750.

The previous prime is 21661042215419. The next prime is 21661042215523. The reversal of 21661042215502 is 20551224016612.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×21661042215502² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5415260553874 + ... + 5415260553877.

It is an arithmetic number, because the mean of its divisors is an integer number (8122890830814).

Almost surely, 2^{21661042215502} is an apocalyptic number.

21661042215502 is a deficient number, since it is larger than the sum of its proper divisors (10830521107754).

21661042215502 is a wasteful number, since it uses less digits than its factorization.

21661042215502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10830521107753.

The product of its (nonzero) digits is 57600, while the sum is 37.

The spelling of 21661042215502 in words is "twenty-one trillion, six hundred sixty-one billion, forty-two million, two hundred fifteen thousand, five hundred two".