21233651 has 2 divisors, whose sum is σ = 21233652. Its totient is φ = 21233650.

The previous prime is 21233647. The next prime is 21233689. The reversal of 21233651 is 15633212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21233651 - 2² = 21233647 is a prime.

It is not a weakly prime, because it can be changed into another prime (21233851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10616825 + 10616826.

It is an arithmetic number, because the mean of its divisors is an integer number (10616826).

Almost surely, 2^21233651 is an apocalyptic number.

21233651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21233651 is an equidigital number, since it uses as much as digits as its factorization.

21233651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1080, while the sum is 23.

The square root of 21233651 is about 4607.9985894095. The cubic root of 21233651 is about 276.9118609873.

Adding to 21233651 its reverse (15633212), we get a palindrome (36866863).

The spelling of 21233651 in words is "twenty-one million, two hundred thirty-three thousand, six hundred fifty-one".