21075451 has 2 divisors, whose sum is σ = 21075452. Its totient is φ = 21075450.

The previous prime is 21075437. The next prime is 21075463. The reversal of 21075451 is 15457012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21075451 - 2⁵ = 21075419 is a prime.

It is not a weakly prime, because it can be changed into another prime (21075401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10537725 + 10537726.

It is an arithmetic number, because the mean of its divisors is an integer number (10537726).

Almost surely, 2^21075451 is an apocalyptic number.

21075451 is the 2651-st hex number.

21075451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21075451 is an equidigital number, since it uses as much as digits as its factorization.

21075451 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1400, while the sum is 25.

The square root of 21075451 is about 4590.8006926897. The cubic root of 21075451 is about 276.2224410992. Note that the first 3 decimals are identical.

The spelling of 21075451 in words is "twenty-one million, seventy-five thousand, four hundred fifty-one".