21031653 has 4 divisors (see below), whose sum is σ = 28042208. Its totient is φ = 14021100.

The previous prime is 21031639. The next prime is 21031667. The reversal of 21031653 is 35613012.

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 (21031639) and next prime (21031667).

It is not a de Polignac number, because 21031653 - 2¹² = 21027557 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 (21031253) 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, 3505273 + ... + 3505278.

It is an arithmetic number, because the mean of its divisors is an integer number (7010552).

Almost surely, 2^21031653 is an apocalyptic number.

It is an amenable number.

21031653 is a deficient number, since it is larger than the sum of its proper divisors (7010555).

21031653 is an equidigital number, since it uses as much as digits as its factorization.

21031653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7010554.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21031653 is about 4586.0280199755. The cubic root of 21031653 is about 276.0309642849.

Adding to 21031653 its reverse (35613012), we get a palindrome (56644665).

The spelling of 21031653 in words is "twenty-one million, thirty-one thousand, six hundred fifty-three".