21698533 has 2 divisors, whose sum is σ = 21698534. Its totient is φ = 21698532.

The previous prime is 21698503. The next prime is 21698561. The reversal of 21698533 is 33589612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21511044 + 187489 = 4638^2 + 433^2 .

It is a cyclic number.

It is not a de Polignac number, because 21698533 - 2²¹ = 19601381 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21698492 and 21698501.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21698503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10849266 + 10849267.

It is an arithmetic number, because the mean of its divisors is an integer number (10849267).

Almost surely, 2^21698533 is an apocalyptic number.

It is an amenable number.

21698533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21698533 is an equidigital number, since it uses as much as digits as its factorization.

21698533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 37.

The square root of 21698533 is about 4658.1684168780. The cubic root of 21698533 is about 278.9181596436.

The spelling of 21698533 in words is "twenty-one million, six hundred ninety-eight thousand, five hundred thirty-three".