21471217357 has 2 divisors, whose sum is σ = 21471217358. Its totient is φ = 21471217356.

The previous prime is 21471217351. The next prime is 21471217421. The reversal of 21471217357 is 75371217412.

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., 15323716521 + 6147500836 = 123789^2 + 78406^2 .

It is a cyclic number.

It is not a de Polignac number, because 21471217357 - 2¹¹ = 21471215309 is a prime.

It is a super-2 number, since 2×21471217357² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21471217351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10735608678 + 10735608679.

It is an arithmetic number, because the mean of its divisors is an integer number (10735608679).

Almost surely, 2^21471217357 is an apocalyptic number.

It is an amenable number.

21471217357 is a deficient number, since it is larger than the sum of its proper divisors (1).

21471217357 is an equidigital number, since it uses as much as digits as its factorization.

21471217357 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82320, while the sum is 40.

The spelling of 21471217357 in words is "twenty-one billion, four hundred seventy-one million, two hundred seventeen thousand, three hundred fifty-seven".