21040651 has 2 divisors, whose sum is σ = 21040652. Its totient is φ = 21040650.

The previous prime is 21040633. The next prime is 21040673. The reversal of 21040651 is 15604012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21040651 - 2⁹ = 21040139 is a prime.

It is not a weakly prime, because it can be changed into another prime (21040601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520325 + 10520326.

It is an arithmetic number, because the mean of its divisors is an integer number (10520326).

Almost surely, 2^21040651 is an apocalyptic number.

21040651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040651 is an equidigital number, since it uses as much as digits as its factorization.

21040651 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21040651 is about 4587.0089382952. The cubic root of 21040651 is about 276.0703235702.

Adding to 21040651 its reverse (15604012), we get a palindrome (36644663).

The spelling of 21040651 in words is "twenty-one million, forty thousand, six hundred fifty-one".