21554669 has 2 divisors, whose sum is σ = 21554670. Its totient is φ = 21554668.

The previous prime is 21554651. The next prime is 21554671. The reversal of 21554669 is 96645512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21501769 + 52900 = 4637^2 + 230^2 .

It is a cyclic number.

It is not a de Polignac number, because 21554669 - 2²⁰ = 20506093 is a prime.

It is a super-2 number, since 2×21554669² = 929207511399122, which contains 22 as substring.

Together with 21554671, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21554629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777334 + 10777335.

It is an arithmetic number, because the mean of its divisors is an integer number (10777335).

Almost surely, 2^21554669 is an apocalyptic number.

It is an amenable number.

21554669 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554669 is an equidigital number, since it uses as much as digits as its factorization.

21554669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64800, while the sum is 38.

The square root of 21554669 is about 4642.7006149438. The cubic root of 21554669 is about 278.3003714736.

The spelling of 21554669 in words is "twenty-one million, five hundred fifty-four thousand, six hundred sixty-nine".