21061607 has 4 divisors (see below), whose sum is σ = 24070416. Its totient is φ = 18052800.

The previous prime is 21061603. The next prime is 21061609. The reversal of 21061607 is 70616012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21061607 - 2² = 21061603 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21061603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1504394 + ... + 1504407.

It is an arithmetic number, because the mean of its divisors is an integer number (6017604).

Almost surely, 2^21061607 is an apocalyptic number.

21061607 is a deficient number, since it is larger than the sum of its proper divisors (3008809).

21061607 is an equidigital number, since it uses as much as digits as its factorization.

21061607 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3008808.

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 21061607 is about 4589.2926470209. The cubic root of 21061607 is about 276.1619463703.

Adding to 21061607 its reverse (70616012), we get a palindrome (91677619).

The spelling of 21061607 in words is "twenty-one million, sixty-one thousand, six hundred seven".