21343551 has 16 divisors (see below), whose sum is σ = 30233088. Its totient is φ = 13347200.

The previous prime is 21343519. The next prime is 21343579. The reversal of 21343551 is 15534312.

It is a cyclic number.

It is not a de Polignac number, because 21343551 - 2⁵ = 21343519 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21343501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21496 + ... + 22466.

It is an arithmetic number, because the mean of its divisors is an integer number (1889568).

Almost surely, 2^21343551 is an apocalyptic number.

21343551 is a deficient number, since it is larger than the sum of its proper divisors (8889537).

21343551 is a wasteful number, since it uses less digits than its factorization.

21343551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1422.

The product of its digits is 1800, while the sum is 24.

The square root of 21343551 is about 4619.9081159694. The cubic root of 21343551 is about 277.3887810129.

Adding to 21343551 its reverse (15534312), we get a palindrome (36877863).

The spelling of 21343551 in words is "twenty-one million, three hundred forty-three thousand, five hundred fifty-one".