21479561 has 2 divisors, whose sum is σ = 21479562. Its totient is φ = 21479560.

The previous prime is 21479467. The next prime is 21479567. The reversal of 21479561 is 16597412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21335161 + 144400 = 4619^2 + 380^2 .

It is a cyclic number.

It is not a de Polignac number, because 21479561 - 2¹⁴ = 21463177 is a prime.

It is a super-2 number, since 2×21479561² = 922743081505442, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21479567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10739780 + 10739781.

It is an arithmetic number, because the mean of its divisors is an integer number (10739781).

Almost surely, 2^21479561 is an apocalyptic number.

It is an amenable number.

21479561 is a deficient number, since it is larger than the sum of its proper divisors (1).

21479561 is an equidigital number, since it uses as much as digits as its factorization.

21479561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 35.

The square root of 21479561 is about 4634.6047296398. The cubic root of 21479561 is about 277.9767461529.

The spelling of 21479561 in words is "twenty-one million, four hundred seventy-nine thousand, five hundred sixty-one".