21553430 has 16 divisors (see below), whose sum is σ = 39094704. Its totient is φ = 8555040.

The previous prime is 21553421. The next prime is 21553453. The reversal of 21553430 is 3435512.

It is a junction number, because it is equal to n+sod(n) for n = 21553396 and 21553405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6917 + ... + 9536.

It is an arithmetic number, because the mean of its divisors is an integer number (2443419).

Almost surely, 2^21553430 is an apocalyptic number.

21553430 is a deficient number, since it is larger than the sum of its proper divisors (17541274).

21553430 is a wasteful number, since it uses less digits than its factorization.

21553430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16591.

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 21553430 is about 4642.5671777584. The cubic root of 21553430 is about 278.2950389744.

Adding to 21553430 its reverse (3435512), we get a palindrome (24988942).

The spelling of 21553430 in words is "twenty-one million, five hundred fifty-three thousand, four hundred thirty".