21553004 has 18 divisors (see below), whose sum is σ = 41459292. Its totient is φ = 9796600.

The previous prime is 21552983. The next prime is 21553009. The reversal of 21553004 is 40035512.

It is not an unprimeable number, because it can be changed into a prime (21553009) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 21782 + ... + 22749.

It is an arithmetic number, because the mean of its divisors is an integer number (2303294).

Almost surely, 2^21553004 is an apocalyptic number.

It is an amenable number.

21553004 is a deficient number, since it is larger than the sum of its proper divisors (19906288).

21553004 is a wasteful number, since it uses less digits than its factorization.

21553004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44557 (or 44544 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 21553004 is about 4642.5212977433. The cubic root of 21553004 is about 278.2932054771.

Adding to 21553004 its reverse (40035512), we get a palindrome (61588516).

The spelling of 21553004 in words is "twenty-one million, five hundred fifty-three thousand, four".