21672061 has 2 divisors, whose sum is σ = 21672062. Its totient is φ = 21672060.

The previous prime is 21672041. The next prime is 21672073. The reversal of 21672061 is 16027612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19404025 + 2268036 = 4405^2 + 1506^2 .

It is a cyclic number.

It is not a de Polignac number, because 21672061 - 2¹³ = 21663869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21672011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10836030 + 10836031.

It is an arithmetic number, because the mean of its divisors is an integer number (10836031).

Almost surely, 2^21672061 is an apocalyptic number.

It is an amenable number.

21672061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21672061 is an equidigital number, since it uses as much as digits as its factorization.

21672061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21672061 is about 4655.3260895452. The cubic root of 21672061 is about 278.8046876688.

Adding to 21672061 its reverse (16027612), we get a palindrome (37699673).

The spelling of 21672061 in words is "twenty-one million, six hundred seventy-two thousand, sixty-one".