21693641 has 2 divisors, whose sum is σ = 21693642. Its totient is φ = 21693640.

The previous prime is 21693631. The next prime is 21693667. The reversal of 21693641 is 14639612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17673616 + 4020025 = 4204^2 + 2005^2 .

It is a cyclic number.

It is not a de Polignac number, because 21693641 - 2¹⁸ = 21431497 is a prime.

It is a super-2 number, since 2×21693641² = 941228119673762, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21693598 and 21693607.

It is not a weakly prime, because it can be changed into another prime (21693601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10846820 + 10846821.

It is an arithmetic number, because the mean of its divisors is an integer number (10846821).

Almost surely, 2^21693641 is an apocalyptic number.

It is an amenable number.

21693641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21693641 is an equidigital number, since it uses as much as digits as its factorization.

21693641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 32.

The square root of 21693641 is about 4657.6432881877. The cubic root of 21693641 is about 278.8971970868.

The spelling of 21693641 in words is "twenty-one million, six hundred ninety-three thousand, six hundred forty-one".