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21976561 is a prime number
BaseRepresentation
bin101001111010…
…1010111110001
31112100112011201
41103311113301
521111222221
62103011201
7354540415
oct123652761
945315151
1021976561
1111450352
127439b01
134725ca9
142cc0d45
151de1891
hex14f55f1

21976561 has 2 divisors, whose sum is σ = 21976562. Its totient is φ = 21976560.

The previous prime is 21976547. The next prime is 21976567. The reversal of 21976561 is 16567912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15054400 + 6922161 = 3880^2 + 2631^2 .

It is a cyclic number.

It is not a de Polignac number, because 21976561 - 27 = 21976433 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21976561.

It is not a weakly prime, because it can be changed into another prime (21976567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10988280 + 10988281.

It is an arithmetic number, because the mean of its divisors is an integer number (10988281).

Almost surely, 221976561 is an apocalyptic number.

21976561 is the 2097-th centered decagonal number.

It is an amenable number.

21976561 is a deficient number, since it is larger than the sum of its proper divisors (1).

21976561 is an equidigital number, since it uses as much as digits as its factorization.

21976561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22680, while the sum is 37.

The square root of 21976561 is about 4687.9164881640. The cubic root of 21976561 is about 280.1043870989.

The spelling of 21976561 in words is "twenty-one million, nine hundred seventy-six thousand, five hundred sixty-one".