21078601 has 2 divisors, whose sum is σ = 21078602. Its totient is φ = 21078600.

The previous prime is 21078593. The next prime is 21078637. The reversal of 21078601 is 10687012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17472400 + 3606201 = 4180^2 + 1899^2 .

It is a cyclic number.

It is not a de Polignac number, because 21078601 - 2³ = 21078593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21075601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10539300 + 10539301.

It is an arithmetic number, because the mean of its divisors is an integer number (10539301).

Almost surely, 2^21078601 is an apocalyptic number.

It is an amenable number.

21078601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21078601 is an equidigital number, since it uses as much as digits as its factorization.

21078601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 21078601 is about 4591.1437572788. The cubic root of 21078601 is about 276.2362020913.

The spelling of 21078601 in words is "twenty-one million, seventy-eight thousand, six hundred one".