21553124 has 6 divisors (see below), whose sum is σ = 37717974. Its totient is φ = 10776560.

The previous prime is 21553123. The next prime is 21553141. The reversal of 21553124 is 42135512.

It can be written as a sum of positive squares in only one way, i.e., 15745024 + 5808100 = 3968^2 + 2410^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21553124.

It is not an unprimeable number, because it can be changed into a prime (21553123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2694137 + ... + 2694144.

It is an arithmetic number, because the mean of its divisors is an integer number (6286329).

Almost surely, 2^21553124 is an apocalyptic number.

It is an amenable number.

21553124 is a deficient number, since it is larger than the sum of its proper divisors (16164850).

21553124 is a wasteful number, since it uses less digits than its factorization.

21553124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5388285 (or 5388283 counting only the distinct ones).

The product of its digits is 1200, while the sum is 23.

The square root of 21553124 is about 4642.5342217371. The cubic root of 21553124 is about 278.2937219576.

Adding to 21553124 its reverse (42135512), we get a palindrome (63688636).

The spelling of 21553124 in words is "twenty-one million, five hundred fifty-three thousand, one hundred twenty-four".