21486221 has 2 divisors, whose sum is σ = 21486222. Its totient is φ = 21486220.

The previous prime is 21486211. The next prime is 21486239. The reversal of 21486221 is 12268412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14668900 + 6817321 = 3830^2 + 2611^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21486221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21486211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10743110 + 10743111.

It is an arithmetic number, because the mean of its divisors is an integer number (10743111).

Almost surely, 2^21486221 is an apocalyptic number.

It is an amenable number.

21486221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21486221 is an equidigital number, since it uses as much as digits as its factorization.

21486221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1536, while the sum is 26.

The square root of 21486221 is about 4635.3231818289. The cubic root of 21486221 is about 278.0054732114.

The spelling of 21486221 in words is "twenty-one million, four hundred eighty-six thousand, two hundred twenty-one".