21211550 has 12 divisors (see below), whose sum is σ = 39453576. Its totient is φ = 8484600.

The previous prime is 21211507. The next prime is 21211577. The reversal of 21211550 is 5511212.

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 212066 + ... + 212165.

It is an arithmetic number, because the mean of its divisors is an integer number (3287798).

Almost surely, 2^21211550 is an apocalyptic number.

21211550 is a deficient number, since it is larger than the sum of its proper divisors (18242026).

21211550 is a wasteful number, since it uses less digits than its factorization.

21211550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 424243 (or 424238 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 21211550 is about 4605.5998523537. The cubic root of 21211550 is about 276.8157532633.

Adding to 21211550 its reverse (5511212), we get a palindrome (26722762).

The spelling of 21211550 in words is "twenty-one million, two hundred eleven thousand, five hundred fifty".