21612277 has 2 divisors, whose sum is σ = 21612278. Its totient is φ = 21612276.

The previous prime is 21612259. The next prime is 21612313. The reversal of 21612277 is 77221612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15256836 + 6355441 = 3906^2 + 2521^2 .

It is a cyclic number.

It is not a de Polignac number, because 21612277 - 2²³ = 13223669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21612077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10806138 + 10806139.

It is an arithmetic number, because the mean of its divisors is an integer number (10806139).

Almost surely, 2^21612277 is an apocalyptic number.

It is an amenable number.

21612277 is a deficient number, since it is larger than the sum of its proper divisors (1).

21612277 is an equidigital number, since it uses as much as digits as its factorization.

21612277 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2352, while the sum is 28.

The square root of 21612277 is about 4648.9006227279. The cubic root of 21612277 is about 278.5480837142.

Adding to 21612277 its reverse (77221612), we get a palindrome (98833889).

The spelling of 21612277 in words is "twenty-one million, six hundred twelve thousand, two hundred seventy-seven".