21805052 has 6 divisors (see below), whose sum is σ = 38158848. Its totient is φ = 10902524.

The previous prime is 21805037. The next prime is 21805073. The reversal of 21805052 is 25050812.

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, 2725628 + ... + 2725635.

It is an arithmetic number, because the mean of its divisors is an integer number (6359808).

Almost surely, 2^21805052 is an apocalyptic number.

It is an amenable number.

21805052 is a deficient number, since it is larger than the sum of its proper divisors (16353796).

21805052 is a wasteful number, since it uses less digits than its factorization.

21805052 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5451267 (or 5451265 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 23.

The square root of 21805052 is about 4669.5879903906. The cubic root of 21805052 is about 279.3738217782.

Adding to 21805052 its reverse (25050812), we get a palindrome (46855864).

The spelling of 21805052 in words is "twenty-one million, eight hundred five thousand, fifty-two".