21142643 has 2 divisors, whose sum is σ = 21142644. Its totient is φ = 21142642.

The previous prime is 21142613. The next prime is 21142663. The reversal of 21142643 is 34624112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21142643 - 2¹² = 21138547 is a prime.

It is a super-2 number, since 2×21142643² = 894022706050898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21142613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10571321 + 10571322.

It is an arithmetic number, because the mean of its divisors is an integer number (10571322).

Almost surely, 2^21142643 is an apocalyptic number.

21142643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21142643 is an equidigital number, since it uses as much as digits as its factorization.

21142643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 23.

The square root of 21142643 is about 4598.1129825179. The cubic root of 21142643 is about 276.5156771978.

Adding to 21142643 its reverse (34624112), we get a palindrome (55766755).

The spelling of 21142643 in words is "twenty-one million, one hundred forty-two thousand, six hundred forty-three".