21099451 has 2 divisors, whose sum is σ = 21099452. Its totient is φ = 21099450.

The previous prime is 21099427. The next prime is 21099467. The reversal of 21099451 is 15499012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21099451 - 2¹⁷ = 20968379 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21099151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549725 + 10549726.

It is an arithmetic number, because the mean of its divisors is an integer number (10549726).

Almost surely, 2^21099451 is an apocalyptic number.

21099451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21099451 is an equidigital number, since it uses as much as digits as its factorization.

21099451 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 21099451 is about 4593.4138720564. The cubic root of 21099451 is about 276.3272522016.

The spelling of 21099451 in words is "twenty-one million, ninety-nine thousand, four hundred fifty-one".