21005552 has 10 divisors (see below), whose sum is σ = 40698288. Its totient is φ = 10502768.

The previous prime is 21005539. The next prime is 21005561. The reversal of 21005552 is 25550012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 656408 + ... + 656439.

Almost surely, 2^21005552 is an apocalyptic number.

It is an amenable number.

21005552 is a deficient number, since it is larger than the sum of its proper divisors (19692736).

21005552 is a wasteful number, since it uses less digits than its factorization.

21005552 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1312855 (or 1312849 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 20.

The square root of 21005552 is about 4583.1814277857. The cubic root of 21005552 is about 275.9167290625.

Adding to 21005552 its reverse (25550012), we get a palindrome (46555564).

The spelling of 21005552 in words is "twenty-one million, five thousand, five hundred fifty-two".