21721352654 has 16 divisors (see below), whose sum is σ = 32728283280. Its totient is φ = 10811955840.

The previous prime is 21721352647. The next prime is 21721352677. The reversal of 21721352654 is 45625312712.

It is a super-2 number, since 2×21721352654² (a number of 21 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 (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1931552 + ... + 1942764.

It is an arithmetic number, because the mean of its divisors is an integer number (2045517705).

Almost surely, 2^21721352654 is an apocalyptic number.

21721352654 is a deficient number, since it is larger than the sum of its proper divisors (11006930626).

21721352654 is a wasteful number, since it uses less digits than its factorization.

21721352654 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15475.

The product of its digits is 100800, while the sum is 38.

The spelling of 21721352654 in words is "twenty-one billion, seven hundred twenty-one million, three hundred fifty-two thousand, six hundred fifty-four".