21554969 has 2 divisors, whose sum is σ = 21554970. Its totient is φ = 21554968.

The previous prime is 21554947. The next prime is 21554983. The reversal of 21554969 is 96945512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18705625 + 2849344 = 4325^2 + 1688^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21554969 is a prime.

It is a super-2 number, since 2×21554969² = 929233377181922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21554669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777484 + 10777485.

It is an arithmetic number, because the mean of its divisors is an integer number (10777485).

Almost surely, 2^21554969 is an apocalyptic number.

It is an amenable number.

21554969 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554969 is an equidigital number, since it uses as much as digits as its factorization.

21554969 is an evil number, because the sum of its binary digits is even.

The product of its digits is 97200, while the sum is 41.

The square root of 21554969 is about 4642.7329236130. The cubic root of 21554969 is about 278.3016626049.

The spelling of 21554969 in words is "twenty-one million, five hundred fifty-four thousand, nine hundred sixty-nine".