21475687 has 2 divisors, whose sum is σ = 21475688. Its totient is φ = 21475686.

The previous prime is 21475679. The next prime is 21475697. The reversal of 21475687 is 78657412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21475687 - 2³ = 21475679 is a prime.

It is a super-2 number, since 2×21475687² = 922410264243938, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21475637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10737843 + 10737844.

It is an arithmetic number, because the mean of its divisors is an integer number (10737844).

Almost surely, 2^21475687 is an apocalyptic number.

21475687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21475687 is an equidigital number, since it uses as much as digits as its factorization.

21475687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 94080, while the sum is 40.

The square root of 21475687 is about 4634.1867679238. The cubic root of 21475687 is about 277.9600334174.

The spelling of 21475687 in words is "twenty-one million, four hundred seventy-five thousand, six hundred eighty-seven".