21554164 has 24 divisors (see below), whose sum is σ = 40166280. Its totient is φ = 10085376.

The previous prime is 21554161. The next prime is 21554173. The reversal of 21554164 is 46145512.

It can be written as a sum of positive squares in 4 ways, for example, as 18421264 + 3132900 = 4292^2 + 1770^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12592 + ... + 14200.

It is an arithmetic number, because the mean of its divisors is an integer number (1673595).

Almost surely, 2^21554164 is an apocalyptic number.

It is an amenable number.

21554164 is a deficient number, since it is larger than the sum of its proper divisors (18612116).

21554164 is a wasteful number, since it uses less digits than its factorization.

21554164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1827 (or 1825 counting only the distinct ones).

The product of its digits is 4800, while the sum is 28.

The square root of 21554164 is about 4642.6462281763. The cubic root of 21554164 is about 278.2981980422.

Adding to 21554164 its reverse (46145512), we get a palindrome (67699676).

The spelling of 21554164 in words is "twenty-one million, five hundred fifty-four thousand, one hundred sixty-four".