21143851 has 2 divisors, whose sum is σ = 21143852. Its totient is φ = 21143850.

The previous prime is 21143839. The next prime is 21143861. The reversal of 21143851 is 15834112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21143851 - 2⁷ = 21143723 is a prime.

It is a super-2 number, since 2×21143851² = 894124870220402, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21143861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10571925 + 10571926.

It is an arithmetic number, because the mean of its divisors is an integer number (10571926).

Almost surely, 2^21143851 is an apocalyptic number.

21143851 is a deficient number, since it is larger than the sum of its proper divisors (1).

21143851 is an equidigital number, since it uses as much as digits as its factorization.

21143851 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 25.

The square root of 21143851 is about 4598.2443388754. The cubic root of 21143851 is about 276.5209434043.

Adding to 21143851 its reverse (15834112), we get a palindrome (36977963).

The spelling of 21143851 in words is "twenty-one million, one hundred forty-three thousand, eight hundred fifty-one".