21726461 has 2 divisors, whose sum is σ = 21726462. Its totient is φ = 21726460.

The previous prime is 21726427. The next prime is 21726473. The reversal of 21726461 is 16462712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21215236 + 511225 = 4606^2 + 715^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21726461 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21726401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10863230 + 10863231.

It is an arithmetic number, because the mean of its divisors is an integer number (10863231).

Almost surely, 2^21726461 is an apocalyptic number.

It is an amenable number.

21726461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21726461 is an equidigital number, since it uses as much as digits as its factorization.

21726461 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 29.

The square root of 21726461 is about 4661.1651976732. The cubic root of 21726461 is about 279.0377727493.

The spelling of 21726461 in words is "twenty-one million, seven hundred twenty-six thousand, four hundred sixty-one".