21800553 has 4 divisors (see below), whose sum is σ = 29067408. Its totient is φ = 14533700.

The previous prime is 21800551. The next prime is 21800557. The reversal of 21800553 is 35500812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21800553 - 2¹ = 21800551 is a prime.

It is a super-2 number, since 2×21800553² = 950528222211618, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21800551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3633423 + ... + 3633428.

It is an arithmetic number, because the mean of its divisors is an integer number (7266852).

Almost surely, 2^21800553 is an apocalyptic number.

It is an amenable number.

21800553 is a deficient number, since it is larger than the sum of its proper divisors (7266855).

21800553 is an equidigital number, since it uses as much as digits as its factorization.

21800553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7266854.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21800553 is about 4669.1062313895. The cubic root of 21800553 is about 279.3546062117.

The spelling of 21800553 in words is "twenty-one million, eight hundred thousand, five hundred fifty-three".