21121675 has 6 divisors (see below), whose sum is σ = 26190908. Its totient is φ = 16897320.

The previous prime is 21121663. The next prime is 21121679. The reversal of 21121675 is 57612112.

It is not a de Polignac number, because 21121675 - 2⁷ = 21121547 is a prime.

It is a super-2 number, since 2×21121675² = 892250309611250, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 844867 = 21121675 / (2 + 1 + 1 + 2 + 1 + 6 + 7 + 5).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121679) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 422409 + ... + 422458.

Almost surely, 2^21121675 is an apocalyptic number.

21121675 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21121675 is a deficient number, since it is larger than the sum of its proper divisors (5069233).

21121675 is an equidigital number, since it uses as much as digits as its factorization.

21121675 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 844877 (or 844872 counting only the distinct ones).

The product of its digits is 840, while the sum is 25.

The square root of 21121675 is about 4595.8323511634. The cubic root of 21121675 is about 276.4242364308.

Adding to 21121675 its reverse (57612112), we get a palindrome (78733787).

The spelling of 21121675 in words is "twenty-one million, one hundred twenty-one thousand, six hundred seventy-five".