21030657 has 4 divisors (see below), whose sum is σ = 28040880. Its totient is φ = 14020436.

The previous prime is 21030637. The next prime is 21030677. The reversal of 21030657 is 75603012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21030637) and next prime (21030677).

It is a cyclic number.

It is not a de Polignac number, because 21030657 - 2²² = 16836353 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21030637) 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, 3505107 + ... + 3505112.

It is an arithmetic number, because the mean of its divisors is an integer number (7010220).

Almost surely, 2^21030657 is an apocalyptic number.

It is an amenable number.

21030657 is a deficient number, since it is larger than the sum of its proper divisors (7010223).

21030657 is an equidigital number, since it uses as much as digits as its factorization.

21030657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7010222.

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 21030657 is about 4585.9194279882. The cubic root of 21030657 is about 276.0266068658.

Adding to 21030657 its reverse (75603012), we get a palindrome (96633669).

The spelling of 21030657 in words is "twenty-one million, thirty thousand, six hundred fifty-seven".