21699553 has 2 divisors, whose sum is σ = 21699554. Its totient is φ = 21699552.

The previous prime is 21699533. The next prime is 21699581. The reversal of 21699553 is 35599612.

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., 21086464 + 613089 = 4592^2 + 783^2 .

It is a cyclic number.

It is not a de Polignac number, because 21699553 - 2⁵ = 21699521 is a prime.

It is not a weakly prime, because it can be changed into another prime (21699533) 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, 10849776 + 10849777.

It is an arithmetic number, because the mean of its divisors is an integer number (10849777).

Almost surely, 2^21699553 is an apocalyptic number.

It is an amenable number.

21699553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21699553 is an equidigital number, since it uses as much as digits as its factorization.

21699553 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72900, while the sum is 40.

The square root of 21699553 is about 4658.2779006839. The cubic root of 21699553 is about 278.9225300169.

The spelling of 21699553 in words is "twenty-one million, six hundred ninety-nine thousand, five hundred fifty-three".