21477517 has 2 divisors, whose sum is σ = 21477518. Its totient is φ = 21477516.

The previous prime is 21477509. The next prime is 21477523. The reversal of 21477517 is 71577412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11115556 + 10361961 = 3334^2 + 3219^2 .

It is a cyclic number.

It is not a de Polignac number, because 21477517 - 2³ = 21477509 is a prime.

It is a super-2 number, since 2×21477517² = 922567472970578, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21474517) 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, 10738758 + 10738759.

It is an arithmetic number, because the mean of its divisors is an integer number (10738759).

Almost surely, 2^21477517 is an apocalyptic number.

It is an amenable number.

21477517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21477517 is an equidigital number, since it uses as much as digits as its factorization.

21477517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13720, while the sum is 34.

The square root of 21477517 is about 4634.3842093637. The cubic root of 21477517 is about 277.9679284293.

The spelling of 21477517 in words is "twenty-one million, four hundred seventy-seven thousand, five hundred seventeen".