21554541 has 12 divisors (see below), whose sum is σ = 31299840. Its totient is φ = 14293320.

The previous prime is 21554539. The next prime is 21554543. The reversal of 21554541 is 14545512.

It is an interprime number because it is at equal distance from previous prime (21554539) and next prime (21554543).

It is not a de Polignac number, because 21554541 - 2¹ = 21554539 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554543) 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 11 ways as a sum of consecutive naturals, for example, 4551 + ... + 7988.

It is an arithmetic number, because the mean of its divisors is an integer number (2608320).

Almost surely, 2^21554541 is an apocalyptic number.

It is an amenable number.

21554541 is a deficient number, since it is larger than the sum of its proper divisors (9745299).

21554541 is a wasteful number, since it uses less digits than its factorization.

21554541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12736 (or 12733 counting only the distinct ones).

The product of its digits is 4000, while the sum is 27.

The square root of 21554541 is about 4642.6868298433. The cubic root of 21554541 is about 278.2998205873.

It can be divided in two parts, 215 and 54541, that added together give a square (54756 = 234²).

The spelling of 21554541 in words is "twenty-one million, five hundred fifty-four thousand, five hundred forty-one".